[EXP] Annotation Panel Ribbon

[Mario]

(I think this is the final ribbon I have to create). The Annotation Panel / Sidebar in the Viewer now also uses a modern ribbon:



This makes it look much better and in-line with the dark design used by the Viewer.
And, for the first time, we have tooltips for the ribbon buttons!
Due to the nature of how the 3rd party toolkit implements its toolbars, I was never been able to get tooltips in the Viewer toolbar to work - and I've really tried.

The ribbon (my code) and the tooltips (my code) work just fine.
It was a bit of a stretch to get all this working on all screen resolutions and DPI settings, but I think ribbons are nearly ready for production and will replace toolbars in one of the upcoming releases.