b90b473ee0
We use QCocoaWindow::windowStyleMask to compute a new styleMask for the NSWindow, based on the QWindow flags. However, some styleMask bits we do not control in this function, so we need to preserve them in case they were already set on the NSWindow, as otherwise we end up clearing those bits. We did this already for NSWindowStyleMaskFullScreen, but now we do it for all style mask bits we don't control. This fixes an issue after QCocoaWindow::applyContentBorderThickness() started calling setWindowFlags to control NSWindowStyleMaskTexturedBackground, after the introduction of the Qt::NoTitleBarBackgroundHint window flag in a1e6fed44964a3eb14045bf819d232d6cbad9f59 and then bddc0198297828ba29e5cf4b39e07412a506a551. The symptom was losing the NSWindowStyleMaskDocModalWindow style mask for sheets or other modal windows with a QTabWidget in them, as that widget ends up calling applyContentBorderThickness(). Fixes: QTBUG-134447 Pick-to: 6.9 dev Change-Id: Ie3e9ca3ff14f84ce70438d3633bd283fb78b9e8c Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io> Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>