Bug 1074798 - Hide horizontal overflow on the homescreen. r=crdlc,kgrandon
Bug 1074798 - Add in-between divider dropping hints. r=crdlc,kgrandon

This simplifies the group rearrangement logic and brings it closer to spec.
Bug 1074798 - Indicate valid drops with group background colour. r=crdlc,kgrandon
Bug 1074798 - Allow dropping an icon before the first group. r=crdlc,kgrandon
Bug 1074798 - Allow dragging expanded groups. r=crdlc,kgrandon

Collapses groups when you long-press to drag them, as per spec.
Bug 1074798 - Add a drop-shadow when dragging a group. r=crdlc,kgrandon
Bug 1074798 - Handle injected contextmenu events in grid dragdrop. r=crdlc,kgrandon
Merge pull request #24566 from Cwiiis/bug1074798-app-grouping-group-dnd

Bug 1074798 - Make creating new groups match spec. r=crdlc,kgrandon