If someone mentions an object in red, I would expect the attached image in color, and being such a small object that it would have sufficient resolution to identify its details. Anyway, as far as I remember from Proteus ISIS, this should be the button where we must click with the mouse to change the status of the component. I believe that within these objects should appear either arrows ( "↓" and "↑" ) or even signs ( "+" and "-" ) indicating the physical direction of the change on the straps.