Comment # 2 on bug 1047100 from Stefan Hundhammer

Please notice that Qt uses several kinds of hightlights for widgets in the
currently active dialog:

- The widget that currently has the keyboard focus

- A dialog's "default button" if it has any.

The default button is the button that is activated when the user hits the
[Return] key in a dialog, no matter what widget has the keyboard focus. This is
what we see in those screenshots.

What you refer to is (as far as I understand it) the highlighting for the
widget that has the keyboard focus.

Both highlights depend on the widget theme and in addition to that on any
widget style sheet (CSS like) used.