Zoom-in short-cut works in Qt Creator text editor; Zoom-out does not work

I don't know if the "zoom-out" short-cut "Ctl.Shift.+" is supposed to work
inside of Qt Creator Text Editor, but it does not work.
The "zoom-in" short-cut "Ctl.Shift.-" does work

The only way to have it work is to minimize Qt Creator. Then do Ctl.Shift.-outside of
Qt Creator; then click on Creator to restore the panel with the correct zoom-out value.