Initial commit for tooltip

Tooltip was made as it assumed to be. As it was expected, tooltip covers Scrollbar and user can not use the scroll with mouse until tooltip is opened. Please review code and close that pull request https://github.com/vmoyseenko/Dynamo/commit/bfbafeb2c56c40bcb2376a4d341d79e90370282b because it was made in the wrong brach. I apologize about that wrong pull request, that will not happen again.