Removing the title from a QGroupBox

Is it possible to completely remove the title from a QGroupBox? If you just give it an empty title, the label where the title would be still takes up space. It looks like this:

But I want it to look like this instead:

I tried the following things without success:

• Setting the title font size to zero
• Giving the title a size of zero in the stylesheet via setStyleSheet("QGroupBox:title{ max-width: 0; max-height: 0; }");
• Moving the title inside the box via setStyleSheet("QGroupBox:title{ subcontrol-position: center center;}")

Note: You might say that a group box without title is a use case for QFrame. The problem with this is that I want to mix groups/frames with and without title, but the frame has a different visual style than the group box. So if you could tell me how to make QFrame look like QGroupBox that would solve my problems too.

What you see is a bug of the particular style you're using. This pretty much "works" without you having to do anything special on other common styles (e.g. Mac, Windows). If you insist on using the particular style in question, you'll have to patch it yourself and either copy the style into your project, or build entire Qt to have a fixed version.