When CTLOP_DEL is used to delete controls within a specified area (rather than to delete a single control by its ID), it is now more selective about identifying GROUPBOX and FRAME controls that should be deleted. Previously, as long as underlying GROUPBOX or FRAME intersected one of the boundaries of the specified area, it would be deleted. Now, it must be entirely within the specified area in order to deleted. This fixes a problem with overlappying popup frames (such as those created by MSBOXX with the BOX_WIN flag) whereby removing the top frame would delete an overlapping/underlying frame but not all of the controls within it. When the the frame was then restored, the Z order was upside down, so that the frame was obscuring the controls supposed to appear on top of it.
