Handle the case of dragging beyond the last row.  Fixes #15007

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@73446 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Handle the case of dragging beyond the last row.  Fixes #15007

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@73447 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775