* Get rid of string split key display
* Include screen level bindings when no widget is focused
* Add default key display mappings
* Allow user to customise key display at app level
* Better docstring
* Update CHANGELOG.md
* Add get_child_by_id and get_widget_by_id
* Remove redundant code
* Add unit tests for app-level get_child_by_id and get_widget_by_id
* Remove redundant test fixture injection
* Update CHANGELOG
* Enforce uniqueness of ID amongst widget children
* Enforce unique widget IDs amongst widgets mounted together
* Update CHANGELOG.md
* Ensuring unique IDs in a more logical place
* Add docstring to NodeList._get_by_id
* Dont use duplicate IDs in tests, dont mount 2000 widgets
* Mounting less widgets in a unit test
* Reword error message
* Use lower-level depth first search in get_widget_by_id to break out early
* Improvements to width:auto HorizontalLayout
* Fix HorizontalLayout.get_content_width
* Horizontal width auto improvement
* Removing some printxz
* Update snapshot for horizontal layout width auto dock
This seeks to address #1175, where a containing widget with a transparent
background, but with a border, won't show the border. It seems that at the
heart of the Compositor it's taking `is_transparent` (of the widget) as one
of the indicators that mean that it won't be visible. This wouldn't normally
be the case, in that a widget could be transparent (in the background) but
could have visible content.
Note that some snapshot tests failed with this change, but no material
difference was found in those failing snapshot tests.
Adds a method to Widget that allows moving a child of that widget within its
list of children. Options are to move before or after a specific location,
or a sibling widget.
Seeks to implement #1121.
