Font loading timeout on macOS with Qt Backend

[lukas-jung]

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When loading a custom font a message like this occurs: qt.qpa.fonts: Populating font family aliases took 212 ms. Replace uses of missing font family "Plaster" with one that exists to avoid this cost.

[lukas-jung]

Maybe related to #1022

[tronical]

I can't reproduce this :(. The slide_puzzle example works well for me with Qt and it is showing the "Plaster" font as expected. @lukas-jung, do you happen to remember how you launched the slide puzzle to reproduce this?