I have a BenQ FP731 monitor, and the buttons it has are:
I (auto adjust), Exit, Left Arrow, Right Arrow, Enter, and the Power button.
When I press enter, it shows Auto Adjust, Luminance, Geometry, Color, OSD, Language, Recall, and Miscellaneous. There is no button in there that allows me to stretch the screen, it seems that Auto Adjust is the only option that adjusts the screen, but that doesn't do anything for me. Also, Geometry just allows me to move the vertical/horizontal position of the screen, not stretch it either.