BTW, keep in mind that there is no such thing as "universal ref" in C++ standard. It's just a way of thinking about rvalue ref T&& in contexts which provide type deduction for T

since I hate sender() and pb->children().at(0) is even less robust I suggest (assuming you declared QMenu* MainWindow::m):

connect(sel, &QPushButton::released, [=]()->void{ const QSize size = m->sizeHint(); m->popup(sel->mapToGlobal(QPoint(0,-size.height()))); });

P.S.
Looking at this functionality, are you sure QToolButton is not a better choice? see QToolButton::setMenu

@VRonin said in Template: Force const parameter:

why wouldn't a simple static_assert work here?

It definitely would.

You're welcome !

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Hi @clogwog
Use Screen to get the Screen's deimesions. Bind the width and height of root element to it.

Qt developers have investigated this before, and there is a partially-working patch.

There are still a number of important challenges to work through, but devs are focussing on other things at the moment. It is not currently being actively worked on: http://comments.gmane.org/gmane.comp.lib.qt.devel/10327

Hi and welcome to devnet,

That might interest you

Thanks for your answers!
I think I will go with Template specialization.

CU
mts