Implemented smooth system backends
----------------------------------

X	= implemented
P	= partially implemented
U	= unnecessary
n.a.	= not applicable

	Generic	Threads	Timers	Events	Windows	Bitmaps	Surfaces
Win32	X	X	X	X	X	X	X
Xlib	X	n.a.	-	-	P	-	-
SDL	X	X	X	-	n.a.	-	-
POSIX	U	X	-	-	n.a.	n.a.	n.a.
