Listing Qt::Key_Return as ButtonPressKeys hint prevents default buttons in dialogs to work

With commit

https://code.qt.io/cgit/qt/qtbase.git/commit/?id=97eeded5fc8c8ebb476ed4a10d8726dd4d46f181

the ButtonPressKeys hint has been introduced for QPlatformTheme.

For the GnomeTheme this has been implemented with the Qt::Key_Return in the list:

https://code.qt.io/cgit/qt/qtbase.git/commit/?id=43caaca740dd217c13764658d4c286c0d83381e4

This prevents then Return key to work in dialogs with the default button set.

E.g. if a dialog contains a QComboBox that has focus and the user presses return, the ComboBox list is opened while one would expect the default button (usually OK) to be triggered.

This behavior is exposed when using XFCE on X11 (here the Gnome theme is selected). For KDE this defect is not noticable.