Issue #531 and issue #1297 latest PR (Folder dragging expansion + selected files(s) are dropped)

I successfully implemented the feature where when file(s) are dropped onto a treeview folder, the file(s) then become selected. This was in regards to issue #531:

I was asked to create a separate pull request, but I believe github only allows one PR per fork at a time...so I tried creating a new fork and I'm getting something about not being able to automatically merge branches...