A click on this icon opens the following dialog box:
Here you can set for each help element separately whether it should be displayed in front of or behind the layout elements.
Behind here means that the corresponding help element will
be covered by the layout frames. If set to
Front the help
element is drawn in front (on top) of the layout frame.
Clicking on [OK] or pressing [Return] confirms your selection and exits the dialog. [Cancel] discards any changes made.