- In very rare circumstances, poll() to the X connection returns 1 but
no events are read out, causing XNextEvent() in the main loop to wait
infinitely until another event comes, typically affecting fading
process only, causing fading to appear somehow stopped. This commit
adds a (possible) fix.
- Listen to Expose events of the X Composite overlay window if we are
painting to it, to avoid making some parts of the screen blank when
switching out of X screen in --paint-on-overlay mode.
- Drop "fade_fin" member of struct _win, because it's pretty useless.
- Drop unused "root" parameter of expose_root(), move get_time_ms() to
compton.h, etc.
853d20ef56