Update the selection box to use drag and drop.

The old way of doing it was to rely on the user to select the SW point
and then the NE point. This forced the user to have to put the point in
the correct order. This fix will allow the user to click-drag and drop a
bounding box which can be used to calculate the SW and NE points
respectively.  This is the first check in. Still need to clean up before
committing.
Final commit for drag and drop functionality