I am surprised that it is not possible to assign the function "turn flow on/off" to one of the mouse buttons. It is very tedious when I know I will be working on only one screen for some time, to switch flow on and off via options, or to wait for the mouse switch every time I accidentally get too close to the edge of the screen. I have therefore currently placed CTRL on one of the mouse buttons and the switch only with CTRL pressed allowed, but this is not so ideal if you often switch back and forth.