[Qt-interest] How to customize window titlebar?

[Nikos Chantziaras]

I need a window that almost behaves like I want when using QDialog; that 
is, stays on top of its parent (and *only* on top of the parent, not on 
top other windows) and is centered above the parent when shown.

However, when using setWindowFlags(Qt::Dialog) on a QWidget instead, the 
window is not centered above the parent when shown.  I would also need 
to customize it further, by removing the "what's this" help button from 
the window title bar along with the maximize and minimize buttons, 
leaving only the close button.  Resizing the window is OK, but it makes 
zero sense to maximize or minimize it.

I've experimented with stuff like:

setWindowFlags(Qt::Dialog | Qt::CustomizeWindowHint
                | Qt::WindowTitleHint | Qt::WindowCloseButtonHint);

but nothing really works.  When using the "Window Flags" Qt example 
(examples/widgets/windowflags) the only thing that almost does it is 
"Qt::Drawer".  But I don't want a Mac drawer really.  I only want 
something that's initially centered above the parent and offers no 
buttons other that the close button.

Doable?  I'm on KDE, and I suspect it might be a bit broken in this 
regard and that's why I have those problems.