Textualize/textual v0.42.0 on GitHub

Some fixes, improvements, and updates to Pilot (used in testing).

Also some significant improvements in rendering speed.

A few minor breaking changes, see below for details...

[0.42.0] - 2023-11-22

Duplicate CSS errors when parsing CSS from a screen #3581
Added missing blur pseudo class #3439
Fixed visual glitched characters on Windows due to Python limitation #2548
Fixed ScrollableContainer to receive focus #3632
Fixed app-level queries causing a crash when the command palette is active #3633
Fixed outline not rendering correctly in some scenarios (e.g. on Button widgets) #3628
Fixed live-reloading of screen CSS #3454
Select.value could be in an invalid state #3612
Off-by-one in CSS error reporting #3625
Loading indicators and app notifications overlapped in the wrong order #3677
Widgets being loaded are disabled and have their scrolling explicitly disabled too #3677
Method render on a widget could be called before mounting said widget #2914

Exceptions to textual.widgets.select #3614
- InvalidSelectValueError for when setting a Select to an invalid value
- EmptySelectError when creating/setting a Select to have no options when allow_blank is False
Select methods #3614
- clear
- is_blank
Constant Select.BLANK to flag an empty selection #3614
Added restrict, type, max_length, and valid_empty to Input #3657
Added Pilot.mouse_down to simulate MouseDown events #3495
Added Pilot.mouse_up to simulate MouseUp events #3495
Added Widget.is_mounted property #3709

CSS error reporting will no longer provide links to the files in question #3582
inline CSS error reporting will report widget/class variable where the CSS was read from #3582
Breaking change: Setting Select.value to None no longer clears the selection (See Select.BLANK and Select.clear) #3614
Breaking change: Button no longer inherits from Static, now it inherits directly from Widget #3603
Rich markup in markdown headings is now escaped when building the TOC #3689
Mechanics behind mouse clicks. See this for more details. #3495
Breaking change: max/min-width/height now includes padding and border. #3712