Bug 1105850 - Highlight the group being hovered over in edit mode. r=crdlc
Bug 1105850 - Test that hovered groups are highlighted. r=crdlc

Make sure that when hovering an item over a group, it gets highlighted.
Merge pull request #26676 from Cwiiis/bug1105850-highlight-hovered-group

Bug 1105850 - Highlight the group being hovered over in edit mode. r=crdlc