mixxx.exe --controller-preview-screens -> Attempting to create QWindow-based QOffscreenSurface outside the gui thread.

[JoergAtGithub]

Bug Description

If I enable the Dummy (Device Screens) mapping in the controller preference and press Apply, Mixxx always crashes within seconds. Sometimes I see the rendered screen, sometimes it crashs immediatly.
I guess the reason is, that for the preview the rendering must be done in the Main thread, as this has the GUI context for the main screen, where the preview is displayed.

PS D:\mixxx\build\x64__legacy> .\mixxx.exe --controller-preview-screens
PS D:\mixxx\build\x64__legacy> Using preferences ScaleFactor 1
Loading resources from  "D:/mixxx/res/"
Configuration file is at the current version "2.6.0-alpha"
BroadcastSettings - Found 1 profile(s)
warning [Main] Failed to add font: "OpenSans-Bold.ttf"
warning [Main] Failed to add font: "OpenSans-Regular.ttf"
warning [Main] Failed to add font: "OpenSans-Semibold.ttf"
warning [Main] Failed to add font: "Ubuntu-B.ttf"
warning [Main] Failed to add font: "Ubuntu-R.ttf"
Failed to load libjack DLL: -1532570656libjack not found, so do not try to load  jack_client_open ffs  !
warning [CachingReaderWorker 15] BpmControl::trackBeatsUpdated
warning [CachingReaderWorker 42] BpmControl::trackBeatsUpdated
warning [Controller] QObject: Cannot create children for a parent that is in a different thread.
(Parent is QQuickRootItem(0x20fefebe100), parent's thread is QThread(0x20fdd7a08c0), current thread is QThread(0x20fa0094f10)
warning [Controller] QObject::installEventFilter(): Cannot filter events for objects in a different thread.
warning [CtrlScreen_main] Attempting to create QWindow-based QOffscreenSurface outside the gui thread. Expect failures.
warning [CtrlScreen_jog] Attempting to create QWindow-based QOffscreenSurface outside the gui thread. Expect failures.
warning [CtrlScreen_jog] QWindowsContext::windowsProc: No Qt Window found for event 0x83 (WM_NCCALCSIZE), hwnd=0x0x2070a98.
warning [CtrlScreen_jog] QWindowsContext::windowsProc: No Qt Window found for event 0x5 (WM_SIZE), hwnd=0x0x2070a98.
warning [CtrlScreen_jog] QWindowsContext::windowsProc: No Qt Window found for event 0x3 (WM_MOVE), hwnd=0x0x2070a98.
warning [Controller] Attempting to create QWindow-based QOffscreenSurface outside the gui thread. Expect failures.
warning [Controller] PortMIDI device "Traktor Kontrol Z2 MIDI" already closed
warning [CtrlScreen_main] QObject: Cannot create children for a parent that is in a different thread.
(Parent is QGfxSourceProxy(0x2100dd87e40), parent's thread is QThread(0x20fa0094f10), current thread is QThread(0x20fdd7a08c0)

Version

main

OS

Windows 11