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)