justify wayland's use of gbm in a comment

src/widget/opengl.c

@@ -57,8 +57,10 @@ typedef struct x11opengl {
 #include <wayland-egl-core.h>
 #include <sys/mman.h>
 #include <gbm.h>
-typedef void* EGLLabelKHR;
 
+/* 
+Note that for Wayland we create a GBM buffer manually and handle blitting it ourselves instead of using wayland-egl. Doing this allows us greater freedom over event handling; wayland-egl constantly pumps events, making us have to add a weird exception to wayland.c to make this work. Doing this also allows us to clip the OpenGL widget, something that was harder (impossible) with egl wayland.
+*/
 typedef struct waylandopengl {
 	EGLDisplay	    egl_display;
 	EGLContext	    egl_context;