Three level menu dropdown support

Problem/Motivation

Our current approach of supporting three level menus with horizontal second level and third level in dropdown of second level works fine but we think this is not the best UX solution for users. There is not a lot we can do to improve current horizontal menu approach but we can maybe offer additional solution so projects can pick the best one for their needs.

Proposed resolution

The new solution we are proposing is third level support without second level horizontal. So we will have first level horizontal for big screens as we have it right now. Click or hover on first level will show a dropdown with second level links and click on second level dropdown will show third level dropdown.

We need to figure/discuss how we want to show third level dropdown. Let's note that Bootstrap framework is against this - so maybe do not show third level dropdown as a new dropdown control but expand it in second level - same way as we are doing it for small screens.