* Get selection context from object view for constructing the context in subobject view.
* Implement getSelectionContext for flexible layout provider and remove code that makes flexible layout self selectable.
* Get selection context from object frame when constructing context for frames.
* Disable Add button when selected parent is a flexible layout
* Make 'Add' button working for selected display layouts in a flexible layout.
* fix expand error and fix flexible layout toggle container issue
* Check for parent object before getting composition.
* Drag-drop edit mode from capture handler. Drag-drop composition from bubble handler. Check composability on drag start
* Show drop hints without being in edit mode.
* Don't serialize objects twice on drag
