I just noted that without the '*' it does work, in other words, the following works:

QFrame[styleAsPresetPanel="true"] QPushButton, QFrame[styleAsPresetPanel="true"] QCheckBox { /* stylesheet */ }

Allthough this is enough for me to continue for now, my original question remains. I'd expect this to work with the '*' as well, but that doesn't seem to work. Is that a bug I should file, or are my expectations wrong?

It's more of a limitation than a bug I think.

To OS, by default a window is a rectangle, no matter how you paint it, and stylesheets are just a way to paint it.
To cut out the corners you would need a mask. Something like:

auto frame = new QWidget(parent, Qt::Popup); frame->setStyleSheet("background-color: red; border: 1px solid green; border-radius: 6px;"); QPainterPath path; path.addRoundedRect(frame->rect(), 6, 6); frame->setMask(path.toFillPolygon().toPolygon()); frame->show();

The problem is that the mask is a bitmap (0-1), not an image with alpha, so you get a jagged edges, but for some radii it works pretty well.

@Jakob said:

Am I correct to assume that such a approach requires me to create a custom event type

Yes.

[...] could cause quite some performance loss. Or am I too pessimistic?

Don't know, you'll have to meassure the impact. What I can say is that I used an event filter recently to handle input from a graphics tablet. Processing huge amounts of events in real time was no problem.

HI,
if you use MSVC and not mingw you must replace the line C: \ Qt \ Qt5.4.0 \ Tools \ mingw482_32 \ bin \ mingw32-make.exe by
nmake (cf Qt documentation)
and I believe it's not recommended to use Qt 5.4.0 and MSVC,it's better tou use Qt 5.4.1 (binary compatiblity problems with 5.4.0 and MSVC)