* app/ops_buttons.h: removed a c++ style comment

	* app/paint_funcs.c: applied Craig Wiegert's patch to fix
 	the rounding errors in the scaling code.

	* app/paint_funcs.c: Use a mutex lock in disolve pixels instead of
 	rand_r on linux systems since linux's rand_r appears to be broken.

	* app/bezier_select.c: applied Shuji Narazaki's patch that corrects
 	for layer offsets in bezier_stroke.