A touchpad, or a touchscreen? Menus on touchscreen devices have to be larger so that Windows can tell which item you touched - touchscreens are not as precise as devices which interact with the pointer. Not that I was aware 12.x ever supported touch events, but that seems to be what happened here.
If your Touchmote program actually uses the pointer like a mouse or touchpad then I'm not sure what happened; if it allows you to just point at something on the screen then it's acting like a touchscreen.
Go to opera:config#UserPrefs|EnableTouchUI and set it to 0, scroll down to Save (and click it), then restart Opera to get the old menus back.