A QFrame styled with a border, with a border hover style doesn't always clear the hover style if a QCombo Box on the frame is activated.  It sometimes works, but the problem scenario is easy to reproduce also.

In my case, the frame around the combo box is small and only contains a label along with the combo box.  The styles are defined by stylesheet.  I expected this was related to QTBUG-44400, and would be solved along with that, but that appears to have been given a MacOS-specific solution (via QTBUG-78970), and this problem happens in Linux.

A workaround is to detect when the QComboBox view list is shown and explicitly send a "Leave" event to the QFrame.