Problem: MS-Windows: not possible to highlight the title bar
Solution: Make the title/caption bar configurable by introducing the
'go-C' option value which allows to highlight it using the
TitleBar and TitleBarNC highlighting groups (Mao-Yining).
Introduce titlebar color customization for Windows 11 GUI through
highlight groups and new 'guioptions' flag:
- Add 'C' flag to enable titlebar color customization (opt-in)
- New highlight groups: TitleBar (active) and TitleBarNC (inactive)
- Uses DWMWA_CAPTION_COLOR and DWMWA_TEXT_COLOR DWM attributes
- Dynamically loads dwmapi.dll for Windows 11 compatibility
- Defaults to system colors when set to NONE or feature disabled
closes: #18449
Signed-off-by: Mao-Yining <mao.yining@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
When adding new highlight groups, one needs to make sure to also add a
"default link NewHlGroup ExistingHlGroup" in highlight.c code, so that
when resetting a color scheme the old color won't be left behind.
So add a Makefile in the 'ci' directory that verifies that all
documented '*hl-<groupname>' from the documentation are either reflected
in the source code, or belong to a list of 'known to be ignored'
highlight groups and let that check run as part of the CI test suite.
related: #16676closes: #16678
Signed-off-by: Christ van Willegen <cvwillegen@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
