Show tooltip only when toolbar buttons are minimized to icons

Signed-off-by: Sheik Hassan <solergiga@yahoo.com>
Merge pull request #560 from hassanNS/issue-441

Show tooltip only when toolbar buttons are minimized to icons
Empty and null control values render as '(empty)' and  '(null)'.

Fixes #527.

Signed-off-by: Ryan O'Hara <oharar@email.chop.edu>
Merge pull request #559 from ryanjohara/issue-527

Render empty and null control values render as '(empty)' and '(null)'