Currently, disabled text colors are hardcoded. They look good in Default
and light themes, but no so good in dark ones. This PR adds new
variables for all themes to correctly display disabled text.
This commit adds support the following properties to theming:
Flags:
- IsTitleCenter: true if the title should be centered.
Metrics:
- BorderThickness: The border width.
- BorderRadius: The border corner radius.
Gutter -- a space left of the text, before the ruler -- is not a part of
the ruler, nor should it be treated as such. This commit implements
gutter handling in LibGUI::TextEditor as part of mild cleaning up of the
gutter handling (breakpoint icons) in HackStudio's Editor.
This commit also enables separate theming of the gutter.
