I noticed on Mac when running QT creator in full screen mode that while debugging when I try to select Change Local Display Format from popup menu in Locals and Expression window that further submenu is not visible (possibly off screen) I see little arrow indication that there is submenu (it is visible when not running in full screen mode) that I can change display format.
This is always reproducable in full screen when you try to open popup menu and you clicked close to right screen edge. The popup menu is trying to "fit" to be visible. Trying to select submenu looks like it is opening it "off screen" on right side? making it invisible. Instead of showing submenu on left side.