_NET_WM_STATE_DEMANDS_ATTENTION indicates that some action in or with
the window happened. It's a weaker hint than urgency flag of WM_HINTS,
but some applications and almost all Qt applications use it instead of
WM_HINTS' urgency flag (one example is Skype).
This is mainly useful for the testsuite. The tests can wait until i3 processed
all X11 events and then continue. This eliminates sleep() calls which leads to
a more robust and faster testsuite.
This involves:
• Compiling with xcb-util instead of xcb-{atom,aux} (they merged the libraries)
• Not using xcb-{event,property} anymore (code removed upstream)
• Not using the predefined WINDOW, CARDINEL, … atoms (removed upstream)
• Using the new xcb_icccm_* data types/functions instead of just xcb_*
(for example xcb_icccm_get_wm_hints instead of xcb_get_wm_hints)
Also I refactored the atoms to use x-macros.
