There's now IN_X11_Preinit, IN_X11_Postinit (both for want of better
names), and in_x11_init. The first two are for taking care of
initialization that needs to be done before window creation and between
window creation and mapping (ie, are very specific to X11 stuff) while
in_x11_init takes care of the setup for the input system. This proved
necessary in my XInput experimentation: a passive enter grab takes
effect only when the pointer enters the window, thus setting up the grab
with the pointer already in the window has no effect until the pointer
leaves the window and returns.
