1. A touchscreen interface for a controller comprising: a display panel which displays graphical displays; a touch sensitive panel overlying the display panel which indicates position of a touch over the display panel; interface processing resources coupled to the display panel and the touch sensitive panel which supply an interface display to the display panel having an icon representative of an adjustable parameter used by the controller, said icon having a size and a position on the touch sensitive panel; supply a variable adjustment display to the display panel in response to a touch near the position of said icon, the variable adjustment display overlying said interface display and having a size on the touch sensitive panel larger than the size of said icon; and adjust the adjustable parameter and remove the variable adjustment display from the display panel, in response to a touch sequence on the touch sensitive panel over the variable adjustment display.