When using a mix of decorated and standard borders, we need to check the
type of border before trying to reuse SceneRect objects.

Tooltips were crashing on some widgets. Removed unnecessary call to
`Popup.clear()`.

Previous menus still had callbacks attached to layout changes. These
callbacks need to be removed when finalising the widget.

A recent commit to qtile moved some code to different folders. We need
to update the imports here to match.

Closes #350

Adds a new `ConditionalBorder` which allows users to provide multiple
border styles which are selected based on provided `Match` criteria.

Wayland only as x11 will render black artefacts.

ConditionalBorder adjusts the window size based on default value but it
should adjust based on the previous border width.