macOS 2.3: revert restart to change skin

[ronso0]

Reverts "Preferences Interface: on macOS require restart applying a new skin" f8530b8

maybe #3370 fixed the skin crash, too.
Please test!
Read backup-settings-and-database
and github-pull-requests

[foss-]

Tested build artefact on macOS 10.15.7 and changing skins works fine without crashing and without restarting. This is amazing news after such a long time of issues around changing skins.

[ronso0]

Nice!
@Be-ing Can you give this a shot with your mac, as well?

[Be-ing]

I never encountered the skin change crash bug so there wouldn't be a point to me testing this.

[Be-ing]

@foss- were you able to reproduce the crash with the backtrace crashing in QOpenGLFunctions_2_1::initializeOpenGLFunctions previously?

[foss-]

2.3.0-beta (build 2.3 r7726) crashes on skin change from latenite to deere:

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   QtGui                         	0x000000010372f5f9 QOpenGLContext::format() const + 9
1   QtGui                         	0x0000000103a1defd QOpenGLFunctions_2_1::initializeOpenGLFunctions() + 93
2   org.mixxx.mixxx               	0x00000001025cefe5 GLSLWaveformRendererSignal::GLSLWaveformRendererSignal(WaveformWidgetRenderer*, bool) + 181

[Be-ing]

Great, thanks for testing!

[ronso0]

🎉

[Be-ing]

Unfortunately the bug is back. However, I have identified how to reproduce it. The crash occurs when switching from one OpenGL waveform renderer to another or using an OpenGL waveform renderer and switching skins. It only occurs when spinnies are hidden.