Window comments cleanup
This patch only add some tabs the window.h (only window struct area).
The main change is that moves this block to switchpanel.c, because
is only used there:
((w)->wm_gnustep_attr->flags & GSWindowLevelAttr) && \
((w)->wm_gnustep_attr->window_level == WMMainMenuWindowLevel || \
(w)->wm_gnustep_attr->window_level == WMSubmenuWindowLevel))
The patch also include two comments in the window's image:
- WIcon icon is only used when the window is minimized, else is NULL
- RImage has the window image, used in switchpanel,...