Explicitly handle resizing by leaving all events in the lower right 15x15
corner to Cocoa, if the window shows a resizing indicator.  Some
applications may have widgets allocated in this area.  Generally, these
widgets are likely larger than 15x15 so they can still be hit.  Often
scroll bars are found in this area and these can also be manipulated by
other means.  Since this is the only way of resizing windows on Mac OS X,
it is too important to keep it broken.