We need to reset the color cycle for placeholders before each CSS property test because we need to ensure consistent colouring of the placeholders as tests are added/removed/reordered.
Although there was no visual difference in the output, the snapshot tool was complaining because there are now less things to draw on the screen, thus the snapshots looked different. Hence, the placeholder snapshot needed to be updated.
* 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
* 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.
