How about adding advanced keyboard shortcuts for moving elements in the tree?
- Ctrl+Shift+Left/Right to move element one up/down in the tree, similarly like we can traverse the tree without Ctrl
- Ctrl+Shift+Up/Down to move element to parent container or move element to first subcontainer
Also you could add some productive shortcuts for advanced traversing, like
- Ctrl + Right/Left - traverse to the next/previous item with the same class