* Refactor: introduce pointer down state to replace implicit closure state with an explicit object
* Refactor: use pointer down state for resize handle
* Refactor: use pointer down state for isResizing
* Refactor: use pointer down state for resizing offset
* Refactor: use pointer down state for hit element
* Refactor: move selection handling out of pointer down event handler
* Refactor: move text handling out of pointer down event handler
* Refactor: move linear tools handling out of pointer down event handler
* Refactor: move element creation out of pointer down handler