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diff --git a/twin/compton-tde/common.h b/twin/compton-tde/common.h
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+/*
+ * Compton - a compositor for X11
+ *
+ * Based on `xcompmgr` - Copyright (c) 2003, Keith Packard
+ *
+ * Copyright (c) 2011-2013, Christopher Jeffrey
+ * Copyright (c) 2014 Timothy Pearson <[email protected]>
+ * See LICENSE for more information.
+ *
+ */
+
+#ifndef COMPTON_COMMON_H
+#define COMPTON_COMMON_H
+
+// === Options ===
+
+// Debug options, enable them using -D in CFLAGS
+// #define DEBUG_REPAINT    1
+// #define DEBUG_EVENTS     1
+// #define DEBUG_RESTACK    1
+// #define DEBUG_WINTYPE    1
+// #define DEBUG_CLIENTWIN  1
+// #define DEBUG_WINDATA    1
+// #define DEBUG_WINMATCH   1
+// #define DEBUG_REDIR      1
+// #define DEBUG_ALLOC_REG  1
+// #define DEBUG_FRAME      1
+// #define DEBUG_LEADER     1
+// #define DEBUG_C2         1
+// #define DEBUG_GLX        1
+// #define DEBUG_GLX_GLSL   1
+// #define DEBUG_GLX_ERR    1
+// #define DEBUG_GLX_MARK   1
+// #define DEBUG_GLX_PAINTREG 1
+// #define MONITOR_REPAINT  1
+
+// Whether to enable PCRE regular expression support in blacklists, enabled
+// by default
+// #define CONFIG_REGEX_PCRE 1
+// Whether to enable JIT support of libpcre. This may cause problems on PaX
+// kernels.
+// #define CONFIG_REGEX_PCRE_JIT 1
+// Whether to enable parsing of configuration files using libconfig.
+// #define CONFIG_LIBCONFIG 1
+// Whether we are using a legacy version of libconfig (1.3.x).
+// #define CONFIG_LIBCONFIG_LEGACY 1
+// Whether to enable DRM VSync support
+// #define CONFIG_VSYNC_DRM 1
+// Whether to enable OpenGL support
+// #define CONFIG_VSYNC_OPENGL 1
+// Whether to enable GLX GLSL support
+// #define CONFIG_VSYNC_OPENGL_GLSL 1
+// Whether to enable GLX FBO support
+// #define CONFIG_VSYNC_OPENGL_FBO 1
+// Whether to enable DBus support with libdbus.
+// #define CONFIG_DBUS 1
+// Whether to enable condition support.
+// #define CONFIG_C2 1
+// Whether to enable X Sync support.
+// #define CONFIG_XSYNC 1
+// Whether to enable GLX Sync support.
+// #define CONFIG_GLX_XSYNC 1
+
+// TDE specific options
+// #define USE_ENV_HOME 1
+#define WRITE_PID_FILE 1
+#define _TDE_COMP_MGR_VERSION_ 3.00
+
+#if !defined(CONFIG_C2) && defined(DEBUG_C2)
+#error Cannot enable c2 debugging without c2 support.
+#endif
+
+#if (!defined(CONFIG_XSYNC) || !defined(CONFIG_VSYNC_OPENGL)) && defined(CONFIG_GLX_SYNC)
+#error Cannot enable GL sync without X Sync / OpenGL support.
+#endif
+
+#ifndef COMPTON_VERSION
+#define COMPTON_VERSION "unknown"
+#endif
+
+// === Includes ===
+
+// For some special functions
+#define _GNU_SOURCE
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/poll.h>
+#include <assert.h>
+#include <time.h>
+#include <ctype.h>
+#include <sys/time.h>
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+#include <X11/Xatom.h>
+#include <X11/extensions/Xcomposite.h>
+#include <X11/extensions/Xdamage.h>
+#include <X11/extensions/Xrender.h>
+#include <X11/extensions/shape.h>
+#include <X11/extensions/Xrandr.h>
+#include <X11/extensions/Xdbe.h>
+#ifdef CONFIG_XSYNC
+#include <X11/extensions/sync.h>
+#endif
+
+#ifdef CONFIG_XINERAMA
+#include <X11/extensions/Xinerama.h>
+#endif
+
+// Workarounds for missing definitions in very old versions of X headers,
+// thanks to consolers for reporting
+#ifndef PictOpDifference
+#define PictOpDifference 0x39
+#endif
+
+// libconfig
+#ifdef CONFIG_LIBCONFIG
+#include <libgen.h>
+#include <libconfig.h>
+#endif
+
+// libdbus
+#ifdef CONFIG_DBUS
+#include <dbus/dbus.h>
+#endif
+
+// libGL
+#ifdef CONFIG_VSYNC_OPENGL
+#if defined(CONFIG_VSYNC_OPENGL_GLSL) || defined(CONFIG_VSYNC_OPENGL_FBO)
+#define GL_GLEXT_PROTOTYPES
+#endif
+
+#include <GL/glx.h>
+
+// Workarounds for missing definitions in some broken GL drivers, thanks to
+// douglasp and consolers for reporting
+#ifndef GL_TEXTURE_RECTANGLE
+#define GL_TEXTURE_RECTANGLE 0x84F5
+#endif
+
+#ifndef GLX_BACK_BUFFER_AGE_EXT
+#define GLX_BACK_BUFFER_AGE_EXT 0x20F4
+#endif
+
+#endif
+
+// === Macros ===
+
+#define MSTR_(s)        #s
+#define MSTR(s)         MSTR_(s)
+
+/// @brief Wrapper for gcc branch prediction builtin, for likely branch.
+#define likely(x)    __builtin_expect(!!(x), 1)
+
+/// @brief Wrapper for gcc branch prediction builtin, for unlikely branch.
+#define unlikely(x)  __builtin_expect(!!(x), 0)
+
+/// Print out an error message.
+#define printf_err(format, ...) \
+  fprintf(stderr, format "\n", ## __VA_ARGS__)
+
+/// Print out an error message with function name.
+#define printf_errf(format, ...) \
+  printf_err("%s" format,  __func__, ## __VA_ARGS__)
+
+/// Print out an error message with function name, and quit with a
+/// specific exit code.
+#define printf_errfq(code, format, ...) { \
+  printf_err("%s" format,  __func__, ## __VA_ARGS__); \
+  exit(code); \
+}
+
+/// Print out a debug message.
+#define printf_dbg(format, ...) \
+  printf(format, ## __VA_ARGS__); \
+  fflush(stdout)
+
+/// Print out a debug message with function name.
+#define printf_dbgf(format, ...) \
+  printf_dbg("%s" format, __func__, ## __VA_ARGS__)
+
+// Use #s here to prevent macro expansion
+/// Macro used for shortening some debugging code.
+#define CASESTRRET(s)   case s: return #s
+
+// === Constants ===
+#if !(COMPOSITE_MAJOR > 0 || COMPOSITE_MINOR >= 2)
+#error libXcomposite version unsupported
+#endif
+
+/// @brief Length of generic buffers.
+#define BUF_LEN 80
+
+#define ROUNDED_PERCENT 0.05
+#define ROUNDED_PIXELS  10
+
+#define OPAQUE 0xffffffff
+#define REGISTER_PROP "_NET_WM_CM_S"
+
+#define TIME_MS_MAX LONG_MAX
+#define FADE_DELTA_TOLERANCE 0.2
+#define SWOPTI_TOLERANCE 3000
+#define TIMEOUT_RUN_TOLERANCE 0.05
+#define WIN_GET_LEADER_MAX_RECURSION 20
+
+#define SEC_WRAP (15L * 24L * 60L * 60L)
+
+#define NS_PER_SEC 1000000000L
+#define US_PER_SEC 1000000L
+#define MS_PER_SEC 1000
+
+#define XRFILTER_CONVOLUTION  "convolution"
+#define XRFILTER_GUASSIAN     "gaussian"
+#define XRFILTER_BINOMIAL     "binomial"
+
+/// @brief Maximum OpenGL FBConfig depth.
+#define OPENGL_MAX_DEPTH 32
+
+/// @brief Maximum OpenGL buffer age.
+#define CGLX_MAX_BUFFER_AGE 5
+
+/// @brief Maximum passes for blur.
+#define MAX_BLUR_PASS 5
+
+// Window flags
+
+// Window size is changed
+#define WFLAG_SIZE_CHANGE   0x0001
+// Window size/position is changed
+#define WFLAG_POS_CHANGE    0x0002
+// Window opacity / dim state changed
+#define WFLAG_OPCT_CHANGE   0x0004
+
+// === Types ===
+
+typedef uint32_t opacity_t;
+typedef long time_ms_t;
+
+typedef enum {
+  WINTYPE_UNKNOWN,
+  WINTYPE_DESKTOP,
+  WINTYPE_DOCK,
+  WINTYPE_TOOLBAR,
+  WINTYPE_MENU,
+  WINTYPE_UTILITY,
+  WINTYPE_SPLASH,
+  WINTYPE_DIALOG,
+  WINTYPE_NORMAL,
+  WINTYPE_DROPDOWN_MENU,
+  WINTYPE_POPUP_MENU,
+  WINTYPE_TOOLTIP,
+  WINTYPE_NOTIFY,
+  WINTYPE_COMBO,
+  WINTYPE_DND,
+  NUM_WINTYPES
+} wintype_t;
+
+/// Enumeration type to represent switches.
+typedef enum {
+  OFF,    // false
+  ON,     // true
+  UNSET
+} switch_t;
+
+/// Structure representing a X geometry.
+typedef struct {
+  int wid;
+  int hei;
+  int x;
+  int y;
+} geometry_t;
+
+/// Enumeration type of window painting mode.
+typedef enum {
+  WMODE_TRANS,
+  WMODE_SOLID,
+  WMODE_ARGB
+} winmode_t;
+
+/// Structure representing needed window updates.
+typedef struct {
+  bool shadow       : 1;
+  bool fade         : 1;
+  bool focus        : 1;
+  bool invert_color : 1;
+} win_upd_t;
+
+/// Structure representing Window property value.
+typedef struct {
+  // All pointers have the same length, right?
+  // I wanted to use anonymous union but it's a GNU extension...
+  union {
+    unsigned char *p8;
+    short *p16;
+    long *p32;
+  } data;
+  unsigned long nitems;
+  Atom type;
+  int format;
+} winprop_t;
+
+typedef struct _ignore {
+  struct _ignore *next;
+  unsigned long sequence;
+} ignore_t;
+
+enum wincond_target {
+  CONDTGT_NAME,
+  CONDTGT_CLASSI,
+  CONDTGT_CLASSG,
+  CONDTGT_ROLE,
+};
+
+enum wincond_type {
+  CONDTP_EXACT,
+  CONDTP_ANYWHERE,
+  CONDTP_FROMSTART,
+  CONDTP_WILDCARD,
+  CONDTP_REGEX_PCRE,
+};
+
+#define CONDF_IGNORECASE 0x0001
+
+/// VSync modes.
+typedef enum {
+  VSYNC_NONE,
+  VSYNC_DRM,
+  VSYNC_OPENGL,
+  VSYNC_OPENGL_OML,
+  VSYNC_OPENGL_SWC,
+  VSYNC_OPENGL_MSWC,
+  NUM_VSYNC,
+} vsync_t;
+
+/// @brief Possible backends of compton.
+enum backend {
+  BKEND_XRENDER,
+  BKEND_GLX,
+  BKEND_XR_GLX_HYBRID,
+  NUM_BKEND,
+};
+
+/// @brief Possible swap methods.
+enum {
+  SWAPM_BUFFER_AGE = -1,
+  SWAPM_UNDEFINED = 0,
+  SWAPM_COPY = 1,
+  SWAPM_EXCHANGE = 2,
+};
+
+typedef struct _glx_texture glx_texture_t;
+
+#ifdef CONFIG_VSYNC_OPENGL
+#ifdef DEBUG_GLX_DEBUG_CONTEXT
+typedef GLXContext (*f_glXCreateContextAttribsARB) (Display *dpy,
+    GLXFBConfig config, GLXContext share_context, Bool direct,
+    const int *attrib_list);
+typedef void (*GLDEBUGPROC) (GLenum source, GLenum type,
+    GLuint id, GLenum severity, GLsizei length, const GLchar* message,
+    GLvoid* userParam);
+typedef void (*f_DebugMessageCallback) (GLDEBUGPROC, void *userParam);
+#endif
+
+typedef int (*f_WaitVideoSync) (int, int, unsigned *);
+typedef int (*f_GetVideoSync) (unsigned *);
+
+typedef Bool (*f_GetSyncValuesOML) (Display* dpy, GLXDrawable drawable, int64_t* ust, int64_t* msc, int64_t* sbc);
+typedef Bool (*f_WaitForMscOML) (Display* dpy, GLXDrawable drawable, int64_t target_msc, int64_t divisor, int64_t remainder, int64_t* ust, int64_t* msc, int64_t* sbc);
+
+typedef int (*f_SwapIntervalSGI) (int interval);
+typedef int (*f_SwapIntervalMESA) (unsigned int interval);
+
+typedef void (*f_BindTexImageEXT) (Display *display, GLXDrawable drawable, int buffer, const int *attrib_list);
+typedef void (*f_ReleaseTexImageEXT) (Display *display, GLXDrawable drawable, int buffer);
+
+typedef void (*f_CopySubBuffer) (Display *dpy, GLXDrawable drawable, int x, int y, int width, int height);
+
+#ifdef CONFIG_GLX_SYNC
+// Looks like duplicate typedef of the same type is safe?
+typedef int64_t GLint64;
+typedef uint64_t GLuint64;
+typedef struct __GLsync *GLsync;
+
+#ifndef GL_SYNC_FLUSH_COMMANDS_BIT
+#define GL_SYNC_FLUSH_COMMANDS_BIT 0x00000001
+#endif
+
+#ifndef GL_TIMEOUT_IGNORED
+#define GL_TIMEOUT_IGNORED 0xFFFFFFFFFFFFFFFFull
+#endif
+
+#ifndef GL_ALREADY_SIGNALED
+#define GL_ALREADY_SIGNALED 0x911A
+#endif
+
+#ifndef GL_TIMEOUT_EXPIRED
+#define GL_TIMEOUT_EXPIRED 0x911B
+#endif
+
+#ifndef GL_CONDITION_SATISFIED
+#define GL_CONDITION_SATISFIED 0x911C
+#endif
+
+#ifndef GL_WAIT_FAILED
+#define GL_WAIT_FAILED 0x911D
+#endif
+
+typedef GLsync (*f_FenceSync) (GLenum condition, GLbitfield flags);
+typedef GLboolean (*f_IsSync) (GLsync sync);
+typedef void (*f_DeleteSync) (GLsync sync);
+typedef GLenum (*f_ClientWaitSync) (GLsync sync, GLbitfield flags,
+    GLuint64 timeout);
+typedef void (*f_WaitSync) (GLsync sync, GLbitfield flags,
+    GLuint64 timeout);
+typedef GLsync (*f_ImportSyncEXT) (GLenum external_sync_type,
+    GLintptr external_sync, GLbitfield flags);
+#endif
+
+#ifdef DEBUG_GLX_MARK
+typedef void (*f_StringMarkerGREMEDY) (GLsizei len, const void *string);
+typedef void (*f_FrameTerminatorGREMEDY) (void);
+#endif
+
+/// @brief Wrapper of a GLX FBConfig.
+typedef struct {
+  GLXFBConfig cfg;
+  GLint texture_fmt;
+  GLint texture_tgts;
+  bool y_inverted;
+} glx_fbconfig_t;
+
+/// @brief Wrapper of a binded GLX texture.
+struct _glx_texture {
+  GLuint texture;
+  GLXPixmap glpixmap;
+  Pixmap pixmap;
+  GLenum target;
+  unsigned width;
+  unsigned height;
+  unsigned depth;
+  bool y_inverted;
+};
+#endif
+
+#ifdef CONFIG_VSYNC_OPENGL_GLSL
+typedef struct {
+  /// Fragment shader for blur.
+  GLuint frag_shader;
+  /// GLSL program for blur.
+  GLuint prog;
+  /// Location of uniform "offset_x" in blur GLSL program.
+  GLint unifm_offset_x;
+  /// Location of uniform "offset_y" in blur GLSL program.
+  GLint unifm_offset_y;
+  /// Location of uniform "factor_center" in blur GLSL program.
+  GLint unifm_factor_center;
+} glx_blur_pass_t;
+
+typedef struct {
+  /// Framebuffer used for blurring.
+  GLuint fbo;
+  /// Textures used for blurring.
+  GLuint textures[2];
+  /// Width of the textures.
+  int width;
+  /// Height of the textures.
+  int height;
+} glx_blur_cache_t;
+#endif
+
+typedef struct {
+  Pixmap pixmap;
+  Picture pict;
+  glx_texture_t *ptex;
+} paint_t;
+
+#define PAINT_INIT { .pixmap = None, .pict = None }
+
+typedef struct {
+  int size;
+  double *data;
+} conv;
+
+/// Linked list type of atoms.
+typedef struct _latom {
+  Atom atom;
+  struct _latom *next;
+} latom_t;
+
+/// A representation of raw region data
+typedef struct {
+  XRectangle *rects;
+  int nrects;
+} reg_data_t;
+
+#define REG_DATA_INIT { NULL, 0 }
+
+struct _timeout_t;
+
+struct _win;
+
+typedef struct _c2_lptr c2_lptr_t;
+
+/// Structure representing all options.
+typedef struct _options_t {
+  // === General ===
+  /// The configuration file we used.
+  char *config_file;
+  /// Path to write PID to.
+  char *write_pid_path;
+  /// The display name we used. NULL means we are using the value of the
+  /// <code>DISPLAY</code> environment variable.
+  char *display;
+  /// Safe representation of display name.
+  char *display_repr;
+  /// The backend in use.
+  enum backend backend;
+  /// Whether to sync X drawing to avoid certain delay issues with
+  /// GLX backend.
+  bool xrender_sync;
+  /// Whether to sync X drawing with X Sync fence.
+  bool xrender_sync_fence;
+  /// Whether to avoid using stencil buffer under GLX backend. Might be
+  /// unsafe.
+  bool glx_no_stencil;
+  /// Whether to copy unmodified regions from front buffer.
+  bool glx_copy_from_front;
+  /// Whether to use glXCopySubBufferMESA() to update screen.
+  bool glx_use_copysubbuffermesa;
+  /// Whether to avoid rebinding pixmap on window damage.
+  bool glx_no_rebind_pixmap;
+  /// GLX swap method we assume OpenGL uses.
+  int glx_swap_method;
+  /// Whether to use GL_EXT_gpu_shader4 to (hopefully) accelerates blurring.
+  bool glx_use_gpushader4;
+  /// Whether to try to detect WM windows and mark them as focused.
+  bool mark_wmwin_focused;
+  /// Whether to mark override-redirect windows as focused.
+  bool mark_ovredir_focused;
+  /// Whether to fork to background.
+  bool fork_after_register;
+  /// Whether to detect rounded corners.
+  bool detect_rounded_corners;
+  /// Whether to paint on X Composite overlay window instead of root
+  /// window.
+  bool paint_on_overlay;
+  /// Resize damage for a specific number of pixels.
+  int resize_damage;
+  /// Whether to unredirect all windows if a full-screen opaque window
+  /// is detected.
+  bool unredir_if_possible;
+  /// List of conditions of windows to ignore as a full-screen window
+  /// when determining if a window could be unredirected.
+  c2_lptr_t *unredir_if_possible_blacklist;
+  /// Delay before unredirecting screen.
+  time_ms_t unredir_if_possible_delay;
+  /// Forced redirection setting through D-Bus.
+  switch_t redirected_force;
+  /// Whether to stop painting. Controlled through D-Bus.
+  switch_t stoppaint_force;
+  /// Whether to enable D-Bus support.
+  bool dbus;
+  /// Path to log file.
+  char *logpath;
+  /// Number of cycles to paint in benchmark mode. 0 for disabled.
+  int benchmark;
+  /// Window to constantly repaint in benchmark mode. 0 for full-screen.
+  Window benchmark_wid;
+  /// A list of conditions of windows not to paint.
+  c2_lptr_t *paint_blacklist;
+  /// Whether to work under synchronized mode for debugging.
+  bool synchronize;
+
+  // === VSync & software optimization ===
+  /// User-specified refresh rate.
+  int refresh_rate;
+  /// Whether to enable refresh-rate-based software optimization.
+  bool sw_opti;
+  /// VSync method to use;
+  vsync_t vsync;
+  /// Whether to enable double buffer.
+  bool dbe;
+  /// Whether to do VSync aggressively.
+  bool vsync_aggressive;
+  /// Whether to use glFinish() instead of glFlush() for (possibly) better
+  /// VSync yet probably higher CPU usage.
+  bool vsync_use_glfinish;
+
+  // === Shadow ===
+  /// Enable/disable shadow for specific window types.
+  bool wintype_shadow[NUM_WINTYPES];
+  /// Red, green and blue tone of the shadow.
+  double shadow_red, shadow_green, shadow_blue;
+  int shadow_radius;
+  int shadow_offset_x, shadow_offset_y;
+  double shadow_opacity;
+  bool clear_shadow;
+  /// Geometry of a region in which shadow is not painted on.
+  geometry_t shadow_exclude_reg_geom;
+  /// Shadow blacklist. A linked list of conditions.
+  c2_lptr_t *shadow_blacklist;
+  /// Whether bounding-shaped window should be ignored.
+  bool shadow_ignore_shaped;
+  /// Whether to respect _TDE_WM_WINDOW_SHADOW.
+  bool respect_prop_shadow;
+  /// Whether to crop shadow to the very Xinerama screen.
+  bool xinerama_shadow_crop;
+
+  // === Fading ===
+  /// Enable/disable fading for specific window types.
+  bool wintype_fade[NUM_WINTYPES];
+  /// How much to fade in in a single fading step.
+  opacity_t fade_in_step;
+  /// How much to fade out in a single fading step.
+  opacity_t fade_out_step;
+  /// Fading time delta. In milliseconds.
+  time_ms_t fade_delta;
+  /// Whether to disable fading on window open/close.
+  bool no_fading_openclose;
+  /// Whether to disable fading on opacity change
+  bool no_fading_opacitychange;
+  /// Fading blacklist. A linked list of conditions.
+  c2_lptr_t *fade_blacklist;
+
+  // === Opacity ===
+  /// Default opacity for specific window types
+  double wintype_opacity[NUM_WINTYPES];
+  /// Default opacity for inactive windows.
+  /// 32-bit integer with the format of _NET_WM_OPACITY. 0 stands for
+  /// not enabled, default.
+  opacity_t inactive_opacity;
+  /// Default opacity for inactive windows.
+  opacity_t active_opacity;
+  /// Whether inactive_opacity overrides the opacity set by window
+  /// attributes.
+  bool inactive_opacity_override;
+  /// Frame opacity. Relative to window opacity, also affects shadow
+  /// opacity.
+  double frame_opacity;
+  /// Whether to detect _NET_WM_OPACITY on client windows. Used on window
+  /// managers that don't pass _NET_WM_OPACITY to frame windows.
+  bool detect_client_opacity;
+  /// Step for pregenerating alpha pictures. 0.01 - 1.0.
+  double alpha_step;
+
+  // === Other window processing ===
+  /// Whether to blur background of semi-transparent / ARGB windows.
+  bool blur_background;
+  /// Whether to blur background when the window frame is not opaque.
+  /// Implies blur_background.
+  bool blur_background_frame;
+  /// Whether to use fixed blur strength instead of adjusting according
+  /// to window opacity.
+  bool blur_background_fixed;
+  /// Background blur blacklist. A linked list of conditions.
+  c2_lptr_t *blur_background_blacklist;
+  /// Blur convolution kernel.
+  XFixed *blur_kerns[MAX_BLUR_PASS];
+  /// How much to dim an inactive window. 0.0 - 1.0, 0 to disable.
+  double inactive_dim;
+  /// Whether to use fixed inactive dim opacity, instead of deciding
+  /// based on window opacity.
+  bool inactive_dim_fixed;
+  /// Conditions of windows to have inverted colors.
+  c2_lptr_t *invert_color_list;
+  /// Rules to change window opacity.
+  c2_lptr_t *opacity_rules;
+
+  // === Focus related ===
+  /// Consider windows of specific types to be always focused.
+  bool wintype_focus[NUM_WINTYPES];
+  /// Whether to use EWMH _NET_ACTIVE_WINDOW to find active window.
+  bool use_ewmh_active_win;
+  /// A list of windows always to be considered focused.
+  c2_lptr_t *focus_blacklist;
+  /// Whether to do window grouping with <code>WM_TRANSIENT_FOR</code>.
+  bool detect_transient;
+  /// Whether to do window grouping with <code>WM_CLIENT_LEADER</code>.
+  bool detect_client_leader;
+
+  // === Calculated ===
+  /// Whether compton needs to track focus changes.
+  bool track_focus;
+  /// Whether compton needs to track window name and class.
+  bool track_wdata;
+  /// Whether compton needs to track window leaders.
+  bool track_leader;
+} options_t;
+
+/// Structure containing all necessary data for a compton session.
+typedef struct _session_t {
+  // === Display related ===
+  /// Display in use.
+  Display *dpy;
+  /// Default screen.
+  int scr;
+  /// Default visual.
+  Visual *vis;
+  /// Default depth.
+  int depth;
+  /// Root window.
+  Window root;
+  /// Height of root window.
+  int root_height;
+  /// Width of root window.
+  int root_width;
+  // Damage of root window.
+  // Damage root_damage;
+  /// X Composite overlay window. Used if <code>--paint-on-overlay</code>.
+  Window overlay;
+  /// Whether the root tile is filled by compton.
+  bool root_tile_fill;
+  /// Picture of the root window background.
+  paint_t root_tile_paint;
+  /// A region of the size of the screen.
+  XserverRegion screen_reg;
+  /// Picture of root window. Destination of painting in no-DBE painting
+  /// mode.
+  Picture root_picture;
+  /// A Picture acting as the painting target.
+  Picture tgt_picture;
+  /// Temporary buffer to paint to before sending to display.
+  paint_t tgt_buffer;
+#ifdef CONFIG_XSYNC
+  XSyncFence tgt_buffer_fence;
+#endif
+  /// DBE back buffer for root window. Used in DBE painting mode.
+  XdbeBackBuffer root_dbe;
+  /// Window ID of the window we register as a symbol.
+  Window reg_win;
+
+  // === Operation related ===
+  /// Program options.
+  options_t o;
+  /// File descriptors to check for reading.
+  fd_set *pfds_read;
+  /// File descriptors to check for writing.
+  fd_set *pfds_write;
+  /// File descriptors to check for exceptions.
+  fd_set *pfds_except;
+  /// Largest file descriptor in fd_set-s above.
+  int nfds_max;
+  /// Linked list of all timeouts.
+  struct _timeout_t *tmout_lst;
+  /// Timeout for delayed unredirection.
+  struct _timeout_t *tmout_unredir;
+  /// Whether we have hit unredirection timeout.
+  bool tmout_unredir_hit;
+  /// Whether we have received an event in this cycle.
+  bool ev_received;
+  /// Whether the program is idling. I.e. no fading, no potential window
+  /// changes.
+  bool idling;
+  /// Program start time.
+  struct timeval time_start;
+  /// The region needs to painted on next paint.
+  XserverRegion all_damage;
+  /// The region damaged on the last paint.
+  XserverRegion all_damage_last[CGLX_MAX_BUFFER_AGE];
+  /// Whether all windows are currently redirected.
+  bool redirected;
+  /// Pre-generated alpha pictures.
+  Picture *alpha_picts;
+  /// Whether all reg_ignore of windows should expire in this paint.
+  bool reg_ignore_expire;
+  /// Time of last fading. In milliseconds.
+  time_ms_t fade_time;
+  /// Head pointer of the error ignore linked list.
+  ignore_t *ignore_head;
+  /// Pointer to the <code>next</code> member of tail element of the error
+  /// ignore linked list.
+  ignore_t **ignore_tail;
+#ifdef CONFIG_VSYNC_OPENGL
+  /// Current GLX Z value.
+  int glx_z;
+#endif
+  // Cached blur convolution kernels.
+  XFixed *blur_kerns_cache[MAX_BLUR_PASS];
+  /// Reset program after next paint.
+  bool reset;
+
+  // === Expose event related ===
+  /// Pointer to an array of <code>XRectangle</code>-s of exposed region.
+  XRectangle *expose_rects;
+  /// Number of <code>XRectangle</code>-s in <code>expose_rects</code>.
+  int size_expose;
+  /// Index of the next free slot in <code>expose_rects</code>.
+  int n_expose;
+
+  // === Window related ===
+  /// Linked list of all windows.
+  struct _win *list;
+  /// Pointer to <code>win</code> of current active window. Used by
+  /// EWMH <code>_NET_ACTIVE_WINDOW</code> focus detection. In theory,
+  /// it's more reliable to store the window ID directly here, just in
+  /// case the WM does something extraordinary, but caching the pointer
+  /// means another layer of complexity.
+  struct _win *active_win;
+  /// Window ID of leader window of currently active window. Used for
+  /// subsidiary window detection.
+  Window active_leader;
+
+  // === Shadow/dimming related ===
+  /// 1x1 black Picture.
+  Picture black_picture;
+  /// 1x1 Picture of the shadow color.
+  Picture cshadow_picture;
+  /// 1x1 white Picture.
+  Picture white_picture;
+  /// Gaussian map of shadow.
+  conv *gaussian_map;
+  // for shadow precomputation
+  /// Shadow depth on one side.
+  int cgsize;
+  /// Pre-computed color table for corners of shadow.
+  unsigned char *shadow_corner;
+  /// Pre-computed color table for a side of shadow.
+  unsigned char *shadow_top;
+  /// A region in which shadow is not painted on.
+  XserverRegion shadow_exclude_reg;
+
+  // === Software-optimization-related ===
+  /// Currently used refresh rate.
+  short refresh_rate;
+  /// Interval between refresh in nanoseconds.
+  long refresh_intv;
+  /// Nanosecond offset of the first painting.
+  long paint_tm_offset;
+
+#ifdef CONFIG_VSYNC_DRM
+  // === DRM VSync related ===
+  /// File descriptor of DRI device file. Used for DRM VSync.
+  int drm_fd;
+#endif
+
+#ifdef CONFIG_VSYNC_OPENGL
+  // === OpenGL related ===
+  /// GLX context.
+  GLXContext glx_context;
+  /// Whether we have GL_ARB_texture_non_power_of_two.
+  bool glx_has_texture_non_power_of_two;
+  /// Pointer to glXGetVideoSyncSGI function.
+  f_GetVideoSync glXGetVideoSyncSGI;
+  /// Pointer to glXWaitVideoSyncSGI function.
+  f_WaitVideoSync glXWaitVideoSyncSGI;
+   /// Pointer to glXGetSyncValuesOML function.
+  f_GetSyncValuesOML glXGetSyncValuesOML;
+  /// Pointer to glXWaitForMscOML function.
+  f_WaitForMscOML glXWaitForMscOML;
+  /// Pointer to glXSwapIntervalSGI function.
+  f_SwapIntervalSGI glXSwapIntervalProc;
+  /// Pointer to glXSwapIntervalMESA function.
+  f_SwapIntervalMESA glXSwapIntervalMESAProc;
+  /// Pointer to glXBindTexImageEXT function.
+  f_BindTexImageEXT glXBindTexImageProc;
+  /// Pointer to glXReleaseTexImageEXT function.
+  f_ReleaseTexImageEXT glXReleaseTexImageProc;
+  /// Pointer to glXCopySubBufferMESA function.
+  f_CopySubBuffer glXCopySubBufferProc;
+#ifdef CONFIG_GLX_SYNC
+  /// Pointer to the glFenceSync() function.
+  f_FenceSync glFenceSyncProc;
+  /// Pointer to the glIsSync() function.
+  f_IsSync glIsSyncProc;
+  /// Pointer to the glDeleteSync() function.
+  f_DeleteSync glDeleteSyncProc;
+  /// Pointer to the glClientWaitSync() function.
+  f_ClientWaitSync glClientWaitSyncProc;
+  /// Pointer to the glWaitSync() function.
+  f_WaitSync glWaitSyncProc;
+  /// Pointer to the glImportSyncEXT() function.
+  f_ImportSyncEXT glImportSyncEXT;
+#endif
+#ifdef DEBUG_GLX_MARK
+  /// Pointer to StringMarkerGREMEDY function.
+  f_StringMarkerGREMEDY glStringMarkerGREMEDY;
+  /// Pointer to FrameTerminatorGREMEDY function.
+  f_FrameTerminatorGREMEDY glFrameTerminatorGREMEDY;
+#endif
+  /// FBConfig-s for GLX pixmap of different depths.
+  glx_fbconfig_t *glx_fbconfigs[OPENGL_MAX_DEPTH + 1];
+#ifdef CONFIG_VSYNC_OPENGL_GLSL
+  glx_blur_pass_t glx_blur_passes[MAX_BLUR_PASS];
+#endif
+#endif
+
+  // === X extension related ===
+  /// Event base number for X Fixes extension.
+  int xfixes_event;
+  /// Error base number for X Fixes extension.
+  int xfixes_error;
+  /// Event base number for X Damage extension.
+  int damage_event;
+  /// Error base number for X Damage extension.
+  int damage_error;
+  /// Event base number for X Render extension.
+  int render_event;
+  /// Error base number for X Render extension.
+  int render_error;
+  /// Event base number for X Composite extension.
+  int composite_event;
+  /// Error base number for X Composite extension.
+  int composite_error;
+  /// Major opcode for X Composite extension.
+  int composite_opcode;
+  /// Whether X Composite NameWindowPixmap is available. Aka if X
+  /// Composite version >= 0.2.
+  bool has_name_pixmap;
+  /// Whether X Shape extension exists.
+  bool shape_exists;
+  /// Event base number for X Shape extension.
+  int shape_event;
+  /// Error base number for X Shape extension.
+  int shape_error;
+  /// Whether X RandR extension exists.
+  bool randr_exists;
+  /// Event base number for X RandR extension.
+  int randr_event;
+  /// Error base number for X RandR extension.
+  int randr_error;
+#ifdef CONFIG_VSYNC_OPENGL
+  /// Whether X GLX extension exists.
+  bool glx_exists;
+  /// Event base number for X GLX extension.
+  int glx_event;
+  /// Error base number for X GLX extension.
+  int glx_error;
+#endif
+  /// Whether X DBE extension exists.
+  bool dbe_exists;
+#ifdef CONFIG_XINERAMA
+  /// Whether X Xinerama extension exists.
+  bool xinerama_exists;
+  /// Xinerama screen info.
+  XineramaScreenInfo *xinerama_scrs;
+  /// Xinerama screen regions.
+  XserverRegion *xinerama_scr_regs;
+  /// Number of Xinerama screens.
+  int xinerama_nscrs;
+#endif
+#ifdef CONFIG_XSYNC
+  /// Whether X Sync extension exists.
+  bool xsync_exists;
+  /// Event base number for X Sync extension.
+  int xsync_event;
+  /// Error base number for X Sync extension.
+  int xsync_error;
+#endif
+  /// Whether X Render convolution filter exists.
+  bool xrfilter_convolution_exists;
+
+  // === Atoms ===
+  /// Atom of property <code>_NET_WM_OPACITY</code>.
+  Atom atom_opacity;
+  /// Atom of <code>_NET_FRAME_EXTENTS</code>.
+  Atom atom_frame_extents;
+  /// Property atom to identify top-level frame window. Currently
+  /// <code>WM_STATE</code>.
+  Atom atom_client;
+  /// Atom of property <code>WM_NAME</code>.
+  Atom atom_name;
+  /// Atom of property <code>_NET_WM_NAME</code>.
+  Atom atom_name_ewmh;
+  /// Atom of property <code>WM_CLASS</code>.
+  Atom atom_class;
+  /// Atom of property <code>WM_WINDOW_ROLE</code>.
+  Atom atom_role;
+  /// Atom of property <code>WM_TRANSIENT_FOR</code>.
+  Atom atom_transient;
+  /// Atom of property <code>WM_CLIENT_LEADER</code>.
+  Atom atom_client_leader;
+  /// Atom of property <code>_NET_ACTIVE_WINDOW</code>.
+  Atom atom_ewmh_active_win;
+  /// Atom of property <code>_TDE_WM_WINDOW_SHADOW</code>.
+  Atom atom_compton_shadow;
+  /// Atom of property <code>_NET_WM_WINDOW_TYPE</code>.
+  Atom atom_win_type;
+  /// Atom of property <code>_KDE_TRANSPARENT_TO_BLACK</code>.
+  Atom atom_win_type_tde_transparent_to_black;
+  /// Atom of property <code>_KDE_TRANSPARENT_TO_DESKTOP</code>.
+  Atom atom_win_type_tde_transparent_to_desktop;
+  /// Array of atoms of all possible window types.
+  Atom atoms_wintypes[NUM_WINTYPES];
+  /// Linked list of additional atoms to track.
+  latom_t *track_atom_lst;
+
+#ifdef CONFIG_DBUS
+  // === DBus related ===
+  // DBus connection.
+  DBusConnection *dbus_conn;
+  // DBus service name.
+  char *dbus_service;
+#endif
+} session_t;
+
+/// Structure representing a top-level window compton manages.
+typedef struct _win {
+  /// Pointer to the next structure in the linked list.
+  struct _win *next;
+  /// Pointer to the next higher window to paint.
+  struct _win *prev_trans;
+
+  // Core members
+  /// ID of the top-level frame window.
+  Window id;
+  /// Window attributes.
+  XWindowAttributes a;
+#ifdef CONFIG_XINERAMA
+  /// Xinerama screen this window is on.
+  int xinerama_scr;
+#endif
+  /// Window visual pict format;
+  XRenderPictFormat *pictfmt;
+  /// Window painting mode.
+  winmode_t mode;
+  /// Whether the window has been damaged at least once.
+  bool damaged;
+#ifdef CONFIG_XSYNC
+  /// X Sync fence of drawable.
+  XSyncFence fence;
+#endif
+  /// Whether the window was damaged after last paint.
+  bool pixmap_damaged;
+  /// Damage of the window.
+  Damage damage;
+  /// Paint info of the window.
+  paint_t paint;
+  /// Bounding shape of the window.
+  XserverRegion border_size;
+  /// Region of the whole window, shadow region included.
+  XserverRegion extents;
+  /// Window flags. Definitions above.
+  int_fast16_t flags;
+  /// Whether there's a pending <code>ConfigureNotify</code> happening
+  /// when the window is unmapped.
+  bool need_configure;
+  /// Queued <code>ConfigureNotify</code> when the window is unmapped.
+  XConfigureEvent queue_configure;
+  /// Region to be ignored when painting. Basically the region where
+  /// higher opaque windows will paint upon. Depends on window frame
+  /// opacity state, window geometry, window mapped/unmapped state,
+  /// window mode, of this and all higher windows.
+  XserverRegion reg_ignore;
+  /// Cached width/height of the window including border.
+  int widthb, heightb;
+  /// Whether the window has been destroyed.
+  bool destroyed;
+  /// Whether the window is bounding-shaped.
+  bool bounding_shaped;
+  /// Whether the window just have rounded corners.
+  bool rounded_corners;
+  /// Whether this window is to be painted.
+  bool to_paint;
+  /// Whether the window is painting excluded.
+  bool paint_excluded;
+  /// Whether the window is unredirect-if-possible excluded.
+  bool unredir_if_possible_excluded;
+  /// Whether this window is in open/close state.
+  bool in_openclose;
+
+  // Client window related members
+  /// ID of the top-level client window of the window.
+  Window client_win;
+  /// Type of the window.
+  wintype_t window_type;
+  /// Whether it looks like a WM window. We consider a window WM window if
+  /// it does not have a decedent with WM_STATE and it is not override-
+  /// redirected itself.
+  bool wmwin;
+  /// Leader window ID of the window.
+  Window leader;
+  /// Cached topmost window ID of the window.
+  Window cache_leader;
+
+  // Focus-related members
+  /// Whether the window is to be considered focused.
+  bool focused;
+  /// Override value of window focus state. Set by D-Bus method calls.
+  switch_t focused_force;
+
+  // Blacklist related members
+  /// Name of the window.
+  char *name;
+  /// Window instance class of the window.
+  char *class_instance;
+  /// Window general class of the window.
+  char *class_general;
+  /// <code>WM_WINDOW_ROLE</code> value of the window.
+  char *role;
+  const c2_lptr_t *cache_sblst;
+  const c2_lptr_t *cache_fblst;
+  const c2_lptr_t *cache_fcblst;
+  const c2_lptr_t *cache_ivclst;
+  const c2_lptr_t *cache_bbblst;
+  const c2_lptr_t *cache_oparule;
+  const c2_lptr_t *cache_pblst;
+  const c2_lptr_t *cache_uipblst;
+
+  // Opacity-related members
+  /// Current window opacity.
+  opacity_t opacity;
+  /// Target window opacity.
+  opacity_t opacity_tgt;
+  /// Cached value of opacity window attribute.
+  opacity_t opacity_prop;
+  /// Cached value of opacity window attribute on client window. For
+  /// broken window managers not transferring client window's
+  /// _NET_WM_OPACITY value
+  opacity_t opacity_prop_client;
+  /// Last window opacity value we set.
+  opacity_t opacity_set;
+
+  // Fading-related members
+  /// Do not fade if it's false. Change on window type change.
+  /// Used by fading blacklist in the future.
+  bool fade;
+  /// Override value of window fade state. Set by D-Bus method calls.
+  switch_t fade_force;
+  /// Callback to be called after fading completed.
+  void (*fade_callback) (session_t *ps, struct _win *w);
+
+  // Frame-opacity-related members
+  /// Current window frame opacity. Affected by window opacity.
+  double frame_opacity;
+  /// Frame widths. Determined by client window attributes.
+  unsigned int left_width, right_width, top_width, bottom_width;
+
+  // Shadow-related members
+  /// Whether a window has shadow. Calculated.
+  bool shadow;
+  /// Override value of window shadow state. Set by D-Bus method calls.
+  switch_t shadow_force;
+  /// Opacity of the shadow. Affected by window opacity and frame opacity.
+  double shadow_opacity;
+  /// X offset of shadow. Affected by commandline argument.
+  int shadow_dx;
+  /// Y offset of shadow. Affected by commandline argument.
+  int shadow_dy;
+  /// Width of shadow. Affected by window size and commandline argument.
+  int shadow_width;
+  /// Height of shadow. Affected by window size and commandline argument.
+  int shadow_height;
+  /// Relative size of shadow.
+  int shadow_size;
+  /// Picture to render shadow. Affected by window size.
+  paint_t shadow_paint;
+  /// The value of _TDE_WM_WINDOW_SHADOW attribute of the window. Below 0 for
+  /// none.
+  long prop_shadow;
+
+  // Dim-related members
+  /// Whether the window is to be dimmed.
+  bool dim;
+
+  /// Whether to invert window color.
+  bool invert_color;
+  /// Override value of window color inversion state. Set by D-Bus method
+  /// calls.
+  switch_t invert_color_force;
+
+  /// Whether to blur window background.
+  bool blur_background;
+
+  /// Whether to show black background
+  bool show_black_background;
+
+  /// Whether to show desktop background
+  bool show_root_tile;
+
+#ifdef CONFIG_VSYNC_OPENGL_GLSL
+  /// Textures and FBO background blur use.
+  glx_blur_cache_t glx_blur_cache;
+#endif
+} win;
+
+/// Temporary structure used for communication between
+/// <code>get_cfg()</code> and <code>parse_config()</code>.
+struct options_tmp {
+  bool no_dock_shadow;
+  bool no_dnd_shadow;
+  double menu_opacity;
+};
+
+/// Structure for a recorded timeout.
+typedef struct _timeout_t {
+  bool enabled;
+  void *data;
+  bool (*callback)(session_t *ps, struct _timeout_t *ptmout);
+  time_ms_t interval;
+  time_ms_t firstrun;
+  time_ms_t lastrun;
+  struct _timeout_t *next;
+} timeout_t;
+
+/// Enumeration for window event hints.
+typedef enum {
+  WIN_EVMODE_UNKNOWN,
+  WIN_EVMODE_FRAME,
+  WIN_EVMODE_CLIENT
+} win_evmode_t;
+
+extern const char * const WINTYPES[NUM_WINTYPES];
+extern const char * const VSYNC_STRS[NUM_VSYNC + 1];
+extern const char * const BACKEND_STRS[NUM_BKEND + 1];
+extern session_t *ps_g;
+
+// == Debugging code ==
+static inline void
+print_timestamp(session_t *ps);
+
+#ifdef DEBUG_ALLOC_REG
+
+#include <execinfo.h>
+#define BACKTRACE_SIZE  5
+
+/**
+ * Print current backtrace, excluding the first two items.
+ *
+ * Stolen from glibc manual.
+ */
+static inline void
+print_backtrace(void) {
+  void *array[BACKTRACE_SIZE];
+  size_t size;
+  char **strings;
+
+  size = backtrace(array, BACKTRACE_SIZE);
+  strings = backtrace_symbols(array, size);
+
+  for (size_t i = 2; i < size; i++)
+     printf ("%s\n", strings[i]);
+
+  free(strings);
+}
+
+/**
+ * Wrapper of <code>XFixesCreateRegion</code>, for debugging.
+ */
+static inline XserverRegion
+XFixesCreateRegion_(Display *dpy, XRectangle *p, int n,
+    const char *func, int line) {
+  XserverRegion reg = XFixesCreateRegion(dpy, p, n);
+  print_timestamp(ps_g);
+  printf("%#010lx: XFixesCreateRegion() in %s():%d\n", reg, func, line);
+  print_backtrace();
+  fflush(stdout);
+  return reg;
+}
+
+/**
+ * Wrapper of <code>XFixesDestroyRegion</code>, for debugging.
+ */
+static inline void
+XFixesDestroyRegion_(Display *dpy, XserverRegion reg,
+    const char *func, int line) {
+  XFixesDestroyRegion(dpy, reg);
+  print_timestamp(ps_g);
+  printf("%#010lx: XFixesDestroyRegion() in %s():%d\n", reg, func, line);
+  fflush(stdout);
+}
+
+#define XFixesCreateRegion(dpy, p, n) XFixesCreateRegion_(dpy, p, n, __func__, __LINE__)
+#define XFixesDestroyRegion(dpy, reg) XFixesDestroyRegion_(dpy, reg, __func__, __LINE__)
+#endif
+
+// === Functions ===
+
+/**
+ * @brief Quit if the passed-in pointer is empty.
+ */
+static inline void *
+allocchk_(const char *func_name, void *ptr) {
+  if (!ptr) {
+    printf_err("%s(): Failed to allocate memory.", func_name);
+    exit(1);
+  }
+  return ptr;
+}
+
+/// @brief Wrapper of allocchk_().
+#define allocchk(ptr) allocchk_(__func__, ptr)
+
+/// @brief Wrapper of malloc().
+#define cmalloc(nmemb, type) ((type *) allocchk(malloc((nmemb) * sizeof(type))))
+
+/// @brief Wrapper of calloc().
+#define ccalloc(nmemb, type) ((type *) allocchk(calloc((nmemb), sizeof(type))))
+
+/// @brief Wrapper of ealloc().
+#define crealloc(ptr, nmemb, type) ((type *) allocchk(realloc((ptr), (nmemb) * sizeof(type))))
+
+/**
+ * Return whether a struct timeval value is empty.
+ */
+static inline bool
+timeval_isempty(struct timeval *ptv) {
+  if (!ptv)
+    return false;
+
+  return ptv->tv_sec <= 0 && ptv->tv_usec <= 0;
+}
+
+/**
+ * Compare a struct timeval with a time in milliseconds.
+ *
+ * @return > 0 if ptv > ms, 0 if ptv == 0, -1 if ptv < ms
+ */
+static inline int
+timeval_ms_cmp(struct timeval *ptv, time_ms_t ms) {
+  assert(ptv);
+
+  // We use those if statement instead of a - expression because of possible
+  // truncation problem from long to int.
+  {
+    long sec = ms / MS_PER_SEC;
+    if (ptv->tv_sec > sec)
+      return 1;
+    if (ptv->tv_sec < sec)
+      return -1;
+  }
+
+  {
+    long usec = ms % MS_PER_SEC * (US_PER_SEC / MS_PER_SEC);
+    if (ptv->tv_usec > usec)
+      return 1;
+    if (ptv->tv_usec < usec)
+      return -1;
+  }
+
+  return 0;
+}
+
+/**
+ * Subtracting two struct timeval values.
+ *
+ * Taken from glibc manual.
+ *
+ * Subtract the `struct timeval' values X and Y,
+ * storing the result in RESULT.
+ * Return 1 if the difference is negative, otherwise 0.
+ */
+static inline int
+timeval_subtract(struct timeval *result,
+                 struct timeval *x,
+                 struct timeval *y) {
+  /* Perform the carry for the later subtraction by updating y. */
+  if (x->tv_usec < y->tv_usec) {
+    long nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1;
+    y->tv_usec -= 1000000 * nsec;
+    y->tv_sec += nsec;
+  }
+
+  if (x->tv_usec - y->tv_usec > 1000000) {
+    long nsec = (x->tv_usec - y->tv_usec) / 1000000;
+    y->tv_usec += 1000000 * nsec;
+    y->tv_sec -= nsec;
+  }
+
+  /* Compute the time remaining to wait.
+     tv_usec is certainly positive. */
+  result->tv_sec = x->tv_sec - y->tv_sec;
+  result->tv_usec = x->tv_usec - y->tv_usec;
+
+  /* Return 1 if result is negative. */
+  return x->tv_sec < y->tv_sec;
+}
+
+/**
+ * Subtracting two struct timespec values.
+ *
+ * Taken from glibc manual.
+ *
+ * Subtract the `struct timespec' values X and Y,
+ * storing the result in RESULT.
+ * Return 1 if the difference is negative, otherwise 0.
+ */
+static inline int
+timespec_subtract(struct timespec *result,
+                 struct timespec *x,
+                 struct timespec *y) {
+  /* Perform the carry for the later subtraction by updating y. */
+  if (x->tv_nsec < y->tv_nsec) {
+    long nsec = (y->tv_nsec - x->tv_nsec) / NS_PER_SEC + 1;
+    y->tv_nsec -= NS_PER_SEC * nsec;
+    y->tv_sec += nsec;
+  }
+
+  if (x->tv_nsec - y->tv_nsec > NS_PER_SEC) {
+    long nsec = (x->tv_nsec - y->tv_nsec) / NS_PER_SEC;
+    y->tv_nsec += NS_PER_SEC * nsec;
+    y->tv_sec -= nsec;
+  }
+
+  /* Compute the time remaining to wait.
+     tv_nsec is certainly positive. */
+  result->tv_sec = x->tv_sec - y->tv_sec;
+  result->tv_nsec = x->tv_nsec - y->tv_nsec;
+
+  /* Return 1 if result is negative. */
+  return x->tv_sec < y->tv_sec;
+}
+
+/**
+ * Get current time in struct timeval.
+ */
+static inline struct timeval __attribute__((const))
+get_time_timeval(void) {
+  struct timeval tv = { 0, 0 };
+
+  gettimeofday(&tv, NULL);
+
+  // Return a time of all 0 if the call fails
+  return tv;
+}
+
+/**
+ * Get current time in struct timespec.
+ *
+ * Note its starting time is unspecified.
+ */
+static inline struct timespec __attribute__((const))
+get_time_timespec(void) {
+  struct timespec tm = { 0, 0 };
+
+  clock_gettime(CLOCK_MONOTONIC, &tm);
+
+  // Return a time of all 0 if the call fails
+  return tm;
+}
+
+
+/**
+ * Print time passed since program starts execution.
+ *
+ * Used for debugging.
+ */
+static inline void
+print_timestamp(session_t *ps) {
+  struct timeval tm, diff;
+
+  if (gettimeofday(&tm, NULL)) return;
+
+  timeval_subtract(&diff, &tm, &ps->time_start);
+  printf("[ %5ld.%02ld ] ", diff.tv_sec, diff.tv_usec / 10000);
+}
+
+/**
+ * Allocate the space and copy a string.
+ */
+static inline char *
+mstrcpy(const char *src) {
+  char *str = cmalloc(strlen(src) + 1, char);
+
+  strcpy(str, src);
+
+  return str;
+}
+
+/**
+ * Allocate the space and copy a string.
+ */
+static inline char *
+mstrncpy(const char *src, unsigned len) {
+  char *str = cmalloc(len + 1, char);
+
+  strncpy(str, src, len);
+  str[len] = '\0';
+
+  return str;
+}
+
+/**
+ * Allocate the space and join two strings.
+ */
+static inline char *
+mstrjoin(const char *src1, const char *src2) {
+  char *str = cmalloc(strlen(src1) + strlen(src2) + 1, char);
+
+  strcpy(str, src1);
+  strcat(str, src2);
+
+  return str;
+}
+
+/**
+ * Allocate the space and join two strings;
+ */
+static inline char *
+mstrjoin3(const char *src1, const char *src2, const char *src3) {
+  char *str = cmalloc(strlen(src1) + strlen(src2)
+        + strlen(src3) + 1, char);
+
+  strcpy(str, src1);
+  strcat(str, src2);
+  strcat(str, src3);
+
+  return str;
+}
+
+/**
+ * Concatenate a string on heap with another string.
+ */
+static inline void
+mstrextend(char **psrc1, const char *src2) {
+  *psrc1 = crealloc(*psrc1, (*psrc1 ? strlen(*psrc1): 0) + strlen(src2) + 1,
+      char);
+
+  strcat(*psrc1, src2);
+}
+
+/**
+ * Normalize an int value to a specific range.
+ *
+ * @param i int value to normalize
+ * @param min minimal value
+ * @param max maximum value
+ * @return normalized value
+ */
+static inline int __attribute__((const))
+normalize_i_range(int i, int min, int max) {
+  if (i > max) return max;
+  if (i < min) return min;
+  return i;
+}
+
+/**
+ * Select the larger integer of two.
+ */
+static inline int __attribute__((const))
+max_i(int a, int b) {
+  return (a > b ? a : b);
+}
+
+/**
+ * Select the smaller integer of two.
+ */
+static inline int __attribute__((const))
+min_i(int a, int b) {
+  return (a > b ? b : a);
+}
+
+/**
+ * Select the larger long integer of two.
+ */
+static inline long __attribute__((const))
+max_l(long a, long b) {
+  return (a > b ? a : b);
+}
+
+/**
+ * Select the smaller long integer of two.
+ */
+static inline long __attribute__((const))
+min_l(long a, long b) {
+  return (a > b ? b : a);
+}
+
+/**
+ * Normalize a double value to a specific range.
+ *
+ * @param d double value to normalize
+ * @param min minimal value
+ * @param max maximum value
+ * @return normalized value
+ */
+static inline double __attribute__((const))
+normalize_d_range(double d, double min, double max) {
+  if (d > max) return max;
+  if (d < min) return min;
+  return d;
+}
+
+/**
+ * Normalize a double value to 0.\ 0 - 1.\ 0.
+ *
+ * @param d double value to normalize
+ * @return normalized value
+ */
+static inline double __attribute__((const))
+normalize_d(double d) {
+  return normalize_d_range(d, 0.0, 1.0);
+}
+
+/**
+ * Parse a VSync option argument.
+ */
+static inline bool
+parse_vsync(session_t *ps, const char *str) {
+  for (vsync_t i = 0; VSYNC_STRS[i]; ++i)
+    if (!strcasecmp(str, VSYNC_STRS[i])) {
+      ps->o.vsync = i;
+      return true;
+    }
+
+  printf_errf("(\"%s\"): Invalid vsync argument.", str);
+  return false;
+}
+
+/**
+ * Parse a backend option argument.
+ */
+static inline bool
+parse_backend(session_t *ps, const char *str) {
+  for (enum backend i = 0; BACKEND_STRS[i]; ++i)
+    if (!strcasecmp(str, BACKEND_STRS[i])) {
+      ps->o.backend = i;
+      return true;
+    }
+  // Keep compatibility with an old revision containing a spelling mistake...
+  if (!strcasecmp(str, "xr_glx_hybird")) {
+    ps->o.backend = BKEND_XR_GLX_HYBRID;
+    return true;
+  }
+  // cju wants to use dashes
+  if (!strcasecmp(str, "xr-glx-hybrid")) {
+    ps->o.backend = BKEND_XR_GLX_HYBRID;
+    return true;
+  }
+  printf_errf("(\"%s\"): Invalid backend argument.", str);
+  return false;
+}
+
+/**
+ * Parse a glx_swap_method option argument.
+ */
+static inline bool
+parse_glx_swap_method(session_t *ps, const char *str) {
+  // Parse alias
+  if (!strcmp("undefined", str)) {
+    ps->o.glx_swap_method = 0;
+    return true;
+  }
+
+  if (!strcmp("copy", str)) {
+    ps->o.glx_swap_method = 1;
+    return true;
+  }
+
+  if (!strcmp("exchange", str)) {
+    ps->o.glx_swap_method = 2;
+    return true;
+  }
+
+  if (!strcmp("buffer-age", str)) {
+    ps->o.glx_swap_method = -1;
+    return true;
+  }
+
+  // Parse number
+  {
+    char *pc = NULL;
+    int age = strtol(str, &pc, 0);
+    if (!pc || str == pc) {
+      printf_errf("(\"%s\"): Invalid number.", str);
+      return false;
+    }
+
+    for (; *pc; ++pc)
+      if (!isspace(*pc)) {
+        printf_errf("(\"%s\"): Trailing characters.", str);
+        return false;
+      }
+
+    if (age > CGLX_MAX_BUFFER_AGE + 1 || age < -1) {
+      printf_errf("(\"%s\"): Number too large / too small.", str);
+      return false;
+    }
+
+    ps->o.glx_swap_method = age;
+  }
+
+  return true;
+}
+
+timeout_t *
+timeout_insert(session_t *ps, time_ms_t interval,
+    bool (*callback)(session_t *ps, timeout_t *ptmout), void *data);
+
+void
+timeout_invoke(session_t *ps, timeout_t *ptmout);
+
+bool
+timeout_drop(session_t *ps, timeout_t *prm);
+
+void
+timeout_reset(session_t *ps, timeout_t *ptmout);
+
+/**
+ * Add a file descriptor to a select() fd_set.
+ */
+static inline bool
+fds_insert_select(fd_set **ppfds, int fd) {
+  assert(fd <= FD_SETSIZE);
+
+  if (!*ppfds) {
+    if ((*ppfds = malloc(sizeof(fd_set)))) {
+      FD_ZERO(*ppfds);
+    }
+    else {
+      fprintf(stderr, "Failed to allocate memory for select() fdset.\n");
+      exit(1);
+    }
+  }
+
+  FD_SET(fd, *ppfds);
+
+  return true;
+}
+
+/**
+ * Add a new file descriptor to wait for.
+ */
+static inline bool
+fds_insert(session_t *ps, int fd, short events) {
+  bool result = true;
+
+  ps->nfds_max = max_i(fd + 1, ps->nfds_max);
+
+  if (POLLIN & events)
+    result = fds_insert_select(&ps->pfds_read, fd) && result;
+  if (POLLOUT & events)
+    result = fds_insert_select(&ps->pfds_write, fd) && result;
+  if (POLLPRI & events)
+    result = fds_insert_select(&ps->pfds_except, fd) && result;
+
+  return result;
+}
+
+/**
+ * Delete a file descriptor to wait for.
+ */
+static inline void
+fds_drop(session_t *ps, int fd, short events) {
+  // Drop fd from respective fd_set-s
+  if (POLLIN & events && ps->pfds_read)
+    FD_CLR(fd, ps->pfds_read);
+  if (POLLOUT & events && ps->pfds_write)
+    FD_CLR(fd, ps->pfds_write);
+  if (POLLPRI & events && ps->pfds_except)
+    FD_CLR(fd, ps->pfds_except);
+}
+
+#define CPY_FDS(key) \
+  fd_set * key = NULL; \
+  if (ps->key) { \
+    key = malloc(sizeof(fd_set)); \
+    memcpy(key, ps->key, sizeof(fd_set)); \
+    if (!key) { \
+      fprintf(stderr, "Failed to allocate memory for copying select() fdset.\n"); \
+      exit(1); \
+    } \
+  } \
+
+/**
+ * Poll for changes.
+ *
+ * poll() is much better than select(), but ppoll() does not exist on
+ * *BSD.
+ */
+static inline int
+fds_poll(session_t *ps, struct timeval *ptv) {
+  // Copy fds
+  CPY_FDS(pfds_read);
+  CPY_FDS(pfds_write);
+  CPY_FDS(pfds_except);
+
+  int ret = select(ps->nfds_max, pfds_read, pfds_write, pfds_except, ptv);
+
+  free(pfds_read);
+  free(pfds_write);
+  free(pfds_except);
+
+  return ret;
+}
+#undef CPY_FDS
+
+/**
+ * Wrapper of XFree() for convenience.
+ *
+ * Because a NULL pointer cannot be passed to XFree(), its man page says.
+ */
+static inline void
+cxfree(void *data) {
+  if (data)
+    XFree(data);
+}
+
+/**
+ * Wrapper of XInternAtom() for convenience.
+ */
+static inline Atom
+get_atom(session_t *ps, const char *atom_name) {
+  return XInternAtom(ps->dpy, atom_name, False);
+}
+
+/**
+ * Return the painting target window.
+ */
+static inline Window
+get_tgt_window(session_t *ps) {
+  return ps->o.paint_on_overlay ? ps->overlay: ps->root;
+}
+
+/**
+ * Find a window from window id in window linked list of the session.
+ */
+static inline win *
+find_win(session_t *ps, Window id) {
+  if (!id)
+    return NULL;
+
+  win *w;
+
+  for (w = ps->list; w; w = w->next) {
+    if (w->id == id && !w->destroyed)
+      return w;
+  }
+
+  return 0;
+}
+
+/**
+ * Find out the WM frame of a client window using existing data.
+ *
+ * @param id window ID
+ * @return struct _win object of the found window, NULL if not found
+ */
+static inline win *
+find_toplevel(session_t *ps, Window id) {
+  if (!id)
+    return NULL;
+
+  for (win *w = ps->list; w; w = w->next) {
+    if (w->client_win == id && !w->destroyed)
+      return w;
+  }
+
+  return NULL;
+}
+
+
+/**
+ * Check if current backend uses XRender for rendering.
+ */
+static inline bool
+bkend_use_xrender(session_t *ps) {
+  return BKEND_XRENDER == ps->o.backend
+    || BKEND_XR_GLX_HYBRID == ps->o.backend;
+}
+
+/**
+ * Check if current backend uses GLX.
+ */
+static inline bool
+bkend_use_glx(session_t *ps) {
+  return BKEND_GLX == ps->o.backend
+    || BKEND_XR_GLX_HYBRID == ps->o.backend;
+}
+
+/**
+ * Check if a window is really focused.
+ */
+static inline bool
+win_is_focused_real(session_t *ps, const win *w) {
+  return IsViewable == w->a.map_state && ps->active_win == w;
+}
+
+/**
+ * Find out the currently focused window.
+ *
+ * @return struct _win object of the found window, NULL if not found
+ */
+static inline win *
+find_focused(session_t *ps) {
+  if (!ps->o.track_focus) return NULL;
+
+  if (ps->active_win && win_is_focused_real(ps, ps->active_win))
+    return ps->active_win;
+  return NULL;
+}
+
+/**
+ * Copies a region.
+ */
+static inline XserverRegion
+copy_region(const session_t *ps, XserverRegion oldregion) {
+  if (!oldregion)
+    return None;
+
+  XserverRegion region = XFixesCreateRegion(ps->dpy, NULL, 0);
+
+  XFixesCopyRegion(ps->dpy, region, oldregion);
+
+  return region;
+}
+
+/**
+ * Destroy a <code>XserverRegion</code>.
+ */
+static inline void
+free_region(session_t *ps, XserverRegion *p) {
+  if (*p) {
+    XFixesDestroyRegion(ps->dpy, *p);
+    *p = None;
+  }
+}
+
+/**
+ * Free all regions in ps->all_damage_last .
+ */
+static inline void
+free_all_damage_last(session_t *ps) {
+  for (int i = 0; i < CGLX_MAX_BUFFER_AGE; ++i)
+    free_region(ps, &ps->all_damage_last[i]);
+}
+
+#ifdef CONFIG_XSYNC
+/**
+ * Free a XSync fence.
+ */
+static inline void
+free_fence(session_t *ps, XSyncFence *pfence) {
+  if (*pfence)
+    XSyncDestroyFence(ps->dpy, *pfence);
+  *pfence = None;
+}
+#else
+#define free_fence(ps, pfence) ((void) 0)
+#endif
+
+/**
+ * Crop a rectangle by another rectangle.
+ *
+ * psrc and pdst cannot be the same.
+ */
+static inline void
+rect_crop(XRectangle *pdst, const XRectangle *psrc, const XRectangle *pbound) {
+  assert(psrc != pdst);
+  pdst->x = max_i(psrc->x, pbound->x);
+  pdst->y = max_i(psrc->y, pbound->y);
+  pdst->width = max_i(0, min_i(psrc->x + psrc->width, pbound->x + pbound->width) - pdst->x);
+  pdst->height = max_i(0, min_i(psrc->y + psrc->height, pbound->y + pbound->height) - pdst->y);
+}
+
+/**
+ * Check if a rectangle includes the whole screen.
+ */
+static inline bool
+rect_is_fullscreen(session_t *ps, int x, int y, unsigned wid, unsigned hei) {
+  return (x <= 0 && y <= 0
+      && (x + wid) >= ps->root_width && (y + hei) >= ps->root_height);
+}
+
+/**
+ * Check if a window is a fullscreen window.
+ *
+ * It's not using w->border_size for performance measures.
+ */
+static inline bool
+win_is_fullscreen(session_t *ps, const win *w) {
+  return rect_is_fullscreen(ps, w->a.x, w->a.y, w->widthb, w->heightb)
+      && !w->bounding_shaped;
+}
+
+/**
+ * Determine if a window has a specific property.
+ *
+ * @param ps current session
+ * @param w window to check
+ * @param atom atom of property to check
+ * @return 1 if it has the attribute, 0 otherwise
+ */
+static inline bool
+wid_has_prop(const session_t *ps, Window w, Atom atom) {
+  Atom type = None;
+  int format;
+  unsigned long nitems, after;
+  unsigned char *data;
+
+  if (Success == XGetWindowProperty(ps->dpy, w, atom, 0, 0, False,
+        AnyPropertyType, &type, &format, &nitems, &after, &data)) {
+    cxfree(data);
+    if (type) return true;
+  }
+
+  return false;
+}
+
+winprop_t
+wid_get_prop_adv(const session_t *ps, Window w, Atom atom, long offset,
+    long length, Atom rtype, int rformat);
+
+/**
+ * Wrapper of wid_get_prop_adv().
+ */
+static inline winprop_t
+wid_get_prop(const session_t *ps, Window wid, Atom atom, long length,
+    Atom rtype, int rformat) {
+  return wid_get_prop_adv(ps, wid, atom, 0L, length, rtype, rformat);
+}
+
+/**
+ * Get the numeric property value from a win_prop_t.
+ */
+static inline long
+winprop_get_int(winprop_t prop) {
+  long tgt = 0;
+
+  if (!prop.nitems)
+    return 0;
+
+  switch (prop.format) {
+    case 8:   tgt = *(prop.data.p8);    break;
+    case 16:  tgt = *(prop.data.p16);   break;
+    case 32:  tgt = *(prop.data.p32);   break;
+    default:  assert(0);
+              break;
+  }
+
+  return tgt;
+}
+
+bool
+wid_get_text_prop(session_t *ps, Window wid, Atom prop,
+    char ***pstrlst, int *pnstr);
+
+/**
+ * Free a <code>winprop_t</code>.
+ *
+ * @param pprop pointer to the <code>winprop_t</code> to free.
+ */
+static inline void
+free_winprop(winprop_t *pprop) {
+  // Empty the whole structure to avoid possible issues
+  if (pprop->data.p8) {
+    cxfree(pprop->data.p8);
+    pprop->data.p8 = NULL;
+  }
+  pprop->nitems = 0;
+}
+
+void
+force_repaint(session_t *ps);
+
+bool
+vsync_init(session_t *ps);
+
+void
+vsync_deinit(session_t *ps);
+
+#ifdef CONFIG_VSYNC_OPENGL
+/** @name GLX
+ */
+///@{
+
+#ifdef CONFIG_GLX_SYNC
+void
+xr_glx_sync(session_t *ps, Drawable d, XSyncFence *pfence);
+#endif
+
+bool
+glx_init(session_t *ps, bool need_render);
+
+void
+glx_destroy(session_t *ps);
+
+void
+glx_on_root_change(session_t *ps);
+
+bool
+glx_init_blur(session_t *ps);
+
+bool
+glx_bind_pixmap(session_t *ps, glx_texture_t **pptex, Pixmap pixmap,
+    unsigned width, unsigned height, unsigned depth);
+
+void
+glx_release_pixmap(session_t *ps, glx_texture_t *ptex);
+
+void
+glx_paint_pre(session_t *ps, XserverRegion *preg);
+
+/**
+ * Check if a texture is binded, or is binded to the given pixmap.
+ */
+static inline bool
+glx_tex_binded(const glx_texture_t *ptex, Pixmap pixmap) {
+  return ptex && ptex->glpixmap && ptex->texture
+    && (!pixmap || pixmap == ptex->pixmap);
+}
+
+void
+glx_set_clip(session_t *ps, XserverRegion reg, const reg_data_t *pcache_reg);
+
+#ifdef CONFIG_VSYNC_OPENGL_GLSL
+bool
+glx_blur_dst(session_t *ps, int dx, int dy, int width, int height, float z,
+    GLfloat factor_center,
+    XserverRegion reg_tgt, const reg_data_t *pcache_reg,
+    glx_blur_cache_t *pbc);
+#endif
+
+bool
+glx_dim_dst(session_t *ps, int dx, int dy, int width, int height, float z,
+    GLfloat factor, XserverRegion reg_tgt, const reg_data_t *pcache_reg);
+
+bool
+glx_render(session_t *ps, const glx_texture_t *ptex,
+    int x, int y, int dx, int dy, int width, int height, int z,
+    double opacity, bool neg,
+    XserverRegion reg_tgt, const reg_data_t *pcache_reg);
+
+bool
+glx_render_specified_color(session_t *ps, int color, int dx, int dy, int width, int height, int z,
+    XserverRegion reg_tgt, const reg_data_t *pcache_reg);
+
+void
+glx_swap_copysubbuffermesa(session_t *ps, XserverRegion reg);
+
+#ifdef CONFIG_VSYNC_OPENGL_GLSL
+GLuint
+glx_create_shader(GLenum shader_type, const char *shader_str);
+
+GLuint
+glx_create_program(const GLuint * const shaders, int nshaders);
+#endif
+
+/**
+ * Free a GLX texture.
+ */
+static inline void
+free_texture_r(session_t *ps, GLuint *ptexture) {
+  if (*ptexture) {
+    assert(ps->glx_context);
+    glDeleteTextures(1, ptexture);
+    *ptexture = 0;
+  }
+}
+
+/**
+ * Free a GLX Framebuffer object.
+ */
+static inline void
+free_glx_fbo(session_t *ps, GLuint *pfbo) {
+#ifdef CONFIG_VSYNC_OPENGL_FBO
+  if (*pfbo) {
+    glDeleteFramebuffers(1, pfbo);
+    *pfbo = 0;
+  }
+#endif
+  assert(!*pfbo);
+}
+
+#ifdef CONFIG_VSYNC_OPENGL_GLSL
+/**
+ * Free data in glx_blur_cache_t on resize.
+ */
+static inline void
+free_glx_bc_resize(session_t *ps, glx_blur_cache_t *pbc) {
+  free_texture_r(ps, &pbc->textures[0]);
+  free_texture_r(ps, &pbc->textures[1]);
+  pbc->width = 0;
+  pbc->height = 0;
+}
+
+/**
+ * Free a glx_blur_cache_t
+ */
+static inline void
+free_glx_bc(session_t *ps, glx_blur_cache_t *pbc) {
+  free_glx_fbo(ps, &pbc->fbo);
+  free_glx_bc_resize(ps, pbc);
+}
+#endif
+#endif
+
+/**
+ * Free a glx_texture_t.
+ */
+static inline void
+free_texture(session_t *ps, glx_texture_t **pptex) {
+  glx_texture_t *ptex = *pptex;
+
+  // Quit if there's nothing
+  if (!ptex)
+    return;
+
+#ifdef CONFIG_VSYNC_OPENGL
+  glx_release_pixmap(ps, ptex);
+
+  free_texture_r(ps, &ptex->texture);
+
+  // Free structure itself
+  free(ptex);
+  *pptex = NULL;
+#endif
+  assert(!*pptex);
+}
+
+/**
+ * Add a OpenGL debugging marker.
+ */
+static inline void
+glx_mark_(session_t *ps, const char *func, XID xid, bool start) {
+#ifdef DEBUG_GLX_MARK
+  if (bkend_use_glx(ps) && ps->glStringMarkerGREMEDY) {
+    if (!func) func = "(unknown)";
+    const char *postfix = (start ? " (start)": " (end)");
+    char *str = malloc((strlen(func) + 12 + 2
+          + strlen(postfix) + 5) * sizeof(char));
+    strcpy(str, func);
+    sprintf(str + strlen(str), "(%#010lx)%s", xid, postfix);
+    ps->glStringMarkerGREMEDY(strlen(str), str);
+    free(str);
+  }
+#endif
+}
+
+#define glx_mark(ps, xid, start) glx_mark_(ps, __func__, xid, start)
+
+/**
+ * Add a OpenGL debugging marker.
+ */
+static inline void
+glx_mark_frame(session_t *ps) {
+#ifdef DEBUG_GLX_MARK
+  if (bkend_use_glx(ps) && ps->glFrameTerminatorGREMEDY)
+    ps->glFrameTerminatorGREMEDY();
+#endif
+}
+
+///@}
+
+#ifdef CONFIG_XSYNC
+#define xr_sync(ps, d, pfence) xr_sync_(ps, d, pfence)
+#else
+#define xr_sync(ps, d, pfence) xr_sync_(ps, d)
+#endif
+
+/**
+ * Synchronizes a X Render drawable to ensure all pending painting requests
+ * are completed.
+ */
+static inline void
+xr_sync_(session_t *ps, Drawable d
+#ifdef CONFIG_XSYNC
+    , XSyncFence *pfence
+#endif
+    ) {
+  if (!ps->o.xrender_sync)
+    return;
+
+  XSync(ps->dpy, False);
+#ifdef CONFIG_XSYNC
+  if (ps->o.xrender_sync_fence && ps->xsync_exists) {
+    // TODO: If everybody just follows the rules stated in X Sync prototype,
+    // we need only one fence per screen, but let's stay a bit cautious right
+    // now
+    XSyncFence tmp_fence = None;
+    if (!pfence)
+      pfence = &tmp_fence;
+    assert(pfence);
+    if (!*pfence)
+      *pfence = XSyncCreateFence(ps->dpy, d, False);
+    if (*pfence) {
+      Bool triggered = False;
+      /* if (XSyncQueryFence(ps->dpy, *pfence, &triggered) && triggered)
+        XSyncResetFence(ps->dpy, *pfence); */
+      // The fence may fail to be created (e.g. because of died drawable)
+      assert(!XSyncQueryFence(ps->dpy, *pfence, &triggered) || !triggered);
+      XSyncTriggerFence(ps->dpy, *pfence);
+      XSyncAwaitFence(ps->dpy, pfence, 1);
+      assert(!XSyncQueryFence(ps->dpy, *pfence, &triggered) || triggered);
+    }
+    else {
+      printf_errf("(%#010lx): Failed to create X Sync fence.", d);
+    }
+    free_fence(ps, &tmp_fence);
+    if (*pfence)
+      XSyncResetFence(ps->dpy, *pfence);
+  }
+#endif
+#ifdef CONFIG_GLX_SYNC
+  xr_glx_sync(ps, d, pfence);
+#endif
+}
+
+/** @name DBus handling
+ */
+///@{
+#ifdef CONFIG_DBUS
+/** @name DBus handling
+ */
+///@{
+bool
+cdbus_init(session_t *ps);
+
+void
+cdbus_destroy(session_t *ps);
+
+void
+cdbus_loop(session_t *ps);
+
+void
+cdbus_ev_win_added(session_t *ps, win *w);
+
+void
+cdbus_ev_win_destroyed(session_t *ps, win *w);
+
+void
+cdbus_ev_win_mapped(session_t *ps, win *w);
+
+void
+cdbus_ev_win_unmapped(session_t *ps, win *w);
+
+void
+cdbus_ev_win_focusout(session_t *ps, win *w);
+
+void
+cdbus_ev_win_focusin(session_t *ps, win *w);
+//!@}
+
+/** @name DBus hooks
+ */
+///@{
+void
+win_set_shadow_force(session_t *ps, win *w, switch_t val);
+
+void
+win_set_fade_force(session_t *ps, win *w, switch_t val);
+
+void
+win_set_focused_force(session_t *ps, win *w, switch_t val);
+
+void
+win_set_invert_color_force(session_t *ps, win *w, switch_t val);
+
+void
+opts_init_track_focus(session_t *ps);
+
+void
+opts_set_no_fading_openclose(session_t *ps, bool newval);
+
+void
+opts_set_no_fading_opacitychange(session_t *ps, bool newval);
+//!@}
+#endif
+
+#ifdef CONFIG_C2
+/** @name c2
+ */
+///@{
+
+c2_lptr_t *
+c2_parsed(session_t *ps, c2_lptr_t **pcondlst, const char *pattern,
+    void *data);
+
+#define c2_parse(ps, pcondlst, pattern) c2_parsed((ps), (pcondlst), (pattern), NULL)
+
+c2_lptr_t *
+c2_free_lptr(c2_lptr_t *lp);
+
+bool
+c2_matchd(session_t *ps, win *w, const c2_lptr_t *condlst,
+    const c2_lptr_t **cache, void **pdata);
+
+#define c2_match(ps, w, condlst, cache) c2_matchd((ps), (w), (condlst), \
+    (cache), NULL)
+#endif
+
+///@}
+
+#endif
+
+/**
+ * @brief Dump raw bytes in HEX format.
+ *
+ * @param data pointer to raw data
+ * @param len length of data
+ */
+static inline void
+hexdump(const char *data, int len) {
+  static const int BYTE_PER_LN = 16;
+
+  if (len <= 0)
+    return;
+
+  // Print header
+  printf("%10s:", "Offset");
+  for (int i = 0; i < BYTE_PER_LN; ++i)
+    printf(" %2d", i);
+  putchar('\n');
+
+  // Dump content
+  for (int offset = 0; offset < len; ++offset) {
+    if (!(offset % BYTE_PER_LN))
+      printf("0x%08x:", offset);
+
+    printf(" %02hhx", data[offset]);
+
+    if ((BYTE_PER_LN - 1) == offset % BYTE_PER_LN)
+      putchar('\n');
+  }
+  if (len % BYTE_PER_LN)
+    putchar('\n');
+
+  fflush(stdout);
+}
+