Fix track color background with Qt6

[ronso0]

Fixes #12355 for me, both with Qt5 and Qt6 (note I didn't see #11630).

So, the issue is that 1ef4e4d

/* Prevent OS-style checkbox from being rendered underneath the custom style. */
WTrackTableView::item,
#LibraryBPMButton::item {
  border: 0px;
}

clears the track color set via BackgroundRole.

Seems it sufficient to call TableItemDelegate::paintItemBackground like it's done for the other delegates.

I don't know how to apply this to the Played checkbox (it's a native QTableView::indicator), so I added a delegate for that, too. Dumb c/p from BPM delegate, without the editor.

Please check if that works also on Windows and macOS @fwcd @JoergAtGithub
Should look good with all skins.

[fwcd]

Looks good to me

[ronso0]

Can someone tell if the last commits makes sense?
I just feeled weird that every delegate includes QTableView etc.

[daschuer]

The last commit has some implications regarding compile time. It includes unnecessarily headers into all cpp files that are including "src/library/tableitemdelegate.h"
The tool https://github.com/include-what-you-use/include-what-you-use points that out suggesting to remove all headers that are not used in the including files itself.

[daschuer]

I have used this: daschuer@7f2c8ed
to do the latest header clean up. Unfortunately it is a bit too aggressive, suggesting to use internal Qt headers.

[ronso0]

Okay, thanks. I reverted that header commit.

Ready to roll if it's been confirmed to fix the issue on Windows, too.

[JoergAtGithub]

I tested on Win11. The track color, checkbbox and padlock symbol appear as expected on all skins!

But there seems to be a missing refresh/update, after the color unassign operation. The update happens delayed, when I select another row:
https://github.com/mixxxdj/mixxx/assets/64457745/d4a3d7de-78ed-4153-844f-c71a509a366c

[ronso0]

Thanks for testing.

The refresh issue occurs also in 2.4 IIRC, and it affects the entire row. This PR only touches the BPM delegate, and the new one, of course.

[JoergAtGithub]

Ok, if it's no regression - than we can merge this! Thank you!