* Declare toolbar api via modifiable property
* Fix addon buttons
* Assign editing areas in a synchronous way
* Restore the Tab shortcut that moves the caret to end
- moveCaretToEnd is called twice now: The moveCaretToEnd calls in
*TextInput causes the caret to be moved to the end when switching back
from the window and back.
- To fix this, I will need the code for saving and restoring locations
from #1377
* Restore selections in the PlainTextInput
* Improve type safety of destroyable
- clearable-array was renamed to destroyable
