Well, Qt does not provide these capabilities. This means that you cannot easily use stylesheets for this purpose. However, there might be OS-specific ways to change the color of the title bar. On Windows (10 and later) you can use DwmSetWindowAttribute to enable dark mode for the title bar. Another way is to get a window without decoration/borders from the OS and then draw the entire title bar yourself using Qt. Then, you can also style the title bar using stylesheets. It might get a little complicated to draw the close and minimize buttons in the correct OS style yourself.

@mcf1lmnfs No, because title bar is not a Qt element, is system made, so I cannot change it via Qt Style Sheets.

Omg, I've just ORed the flags, and now it works as intended.
In QtWidgets it should be:

// To set the window minimized setWindowState(windowState() & ~Qt::WindowActive | Qt::WindowMinimized); // To restore the window from minimized state setWindowState(windowState() & ~Qt::WindowMinimized | Qt::WindowActive);

So in QML it should work in the same way.

That geometryRectangle is irrelevant, as it is used only for the widget with 2 large, red close buttons which is positioned correctly. What I observed via debugging/logging is that code part:

if (isMinimized()) { //emit minimizeAddNewEquipmentDialog(); addEquipmentDialog->showMinimized();//that's 2nd widget }

somehow spoils behavior of the widget, if I recall correctly after manual, separate minimizing call showNormal() simultaneously worked fine for both widgets. Need to confirm that after work, though.