* Register callbacks at message pump level, invoke them after refresh
* Fix a typo
* Code review feedback actions
* call_later callbacks invoked after refresh or on idle
* Fix space key in text input
* Make Widget.on_idle synchronous
* Fix call_later
* Rename PostScreenUpdate to InvokeCallbacks, and only fire if callbacks exist
* Update type hints for InvokeLater callbacks
* Update type signature of call_later callbacks, extract typevar
I had to add a flag in the `_timer` module that allows us to completely disable the "skip" feature of Timers, though - but it shouldn't cause too much trouble 🤞
