prohibit WWaveformViewer getting focused

[ronso0]

so the currently focused widget stays focused, which is crucial for toggling maximize_library
with when any of the library widgets has focus.

https://bugs.launchpad.net/mixxx/+bug/1936926

complements #2289 and #2307

[ronso0]

2.3 is also affected but the sidebar is auto-focused there, so minimizing the library still works.

I'll rebase onto 2.3

[coveralls]

Pull Request Test Coverage Report for Build 1048865715

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.006%) to 28.638%

---

Files with Coverage Reduction	New Missed Lines	%
src/engine/cachingreader/cachingreaderworker.cpp	2	63.48%
src/engine/readaheadmanager.cpp	2	88.79%

Totals
Change from base Build 1047015866:	-0.006%
Covered Lines:	20095
Relevant Lines:	70170

---

💛 - Coveralls

[Swiftb0y]

I can confirm this fixes / works around the bug linked. @Holzhaus do you want to take another look?

[Holzhaus]

Thanks for the quick fix, LGTM and works fine.

@Swiftb0y No, if you can reproduce the original bug and confirmed that this fixes it and the code looks good to you, feel free to merge without my explicit approval :D

Btw, I noticed that the search box is focused by default after starting mixxx. This means that spacebar to maximize the library doesn't work until clicking the tracks table first. No idea if this is intended or a bug, but no big issue either way.

[ronso0]

oh, it wasn't noticed that I actually wanted to target 2.3, but this went into main.
I'll open a new one.

[ronso0]

Btw, I noticed that the search box is focused by default after starting mixxx. This means that spacebar to maximize the library doesn't work until clicking the tracks table first. No idea if this is intended or a bug, but no big issue either way.

I can't reproduce that: no widget has focus, no matter if Mixxx was started in windowed or fullscreen mode (without controller).
btw, pressing Esc will always focus the tracks table.