The following fixes incorporated:
1. Temporary fix for cancelling  textEdit docWidget: Removed the option to
   delete the window.
2. negative tests: handled errors created when one tried to do export or
   cancel export when there was no tree widget.
3. The cursor now automatically goes to the end of the message and imginfo windows,
   displaying the latest.
Merge pull request #88 from sunithamisra/master

Miscellaneous fixes (see description):