Support custom title bar!

Qt does not offer anyway to make a custom title bar.

One need to do 

    setWindowFlags(windowFlags() | Qt::FramelessWindowHint | Qt::Window); 

then try to implement all the native window functionalities manually. Which on top of being annoyingly hard, is made even harder with Qt6.

Why? There are virtually no mainstream application that do not have a custom title bar : Chrome, Mozilla, Visual Studio, Blender, solidworks, microsoft office... The list is endless. But can you name such mainstream apps that do NOT have a custom title bar? Any?

It is even key for an application to look professional.

That Qt does not offer support for this is simply ridiculous.

It should be as easy as : 

mainwindow->setTitleBarWidget(myTitleBarWidget)

That should have been done 15 years ago.