QT 5.12 introduced a regression, where a QT program wouldn't show its
tray icon, if there was no tray bar during program startup. (QTBUG-73459)

QT 5.12 introduced a regression, where qtwebengine applications would
freeze in some wayland compositors if a surface from the instance was not
visible (for example having a qutebrowser window on another workspace in
sway would freeze all qutebrowser windows).

Both got fixed already in Qt 5.12.4, but according to #57042 and its
sibling issues/PRs it doesn't seem to get fixed in near future for
nixpkgs.

Motivation for this change

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @