Scales and shifts data to map visible range into specified range. Sets or retrieves variable's transformed coordinate range. Return indices of current selection. Sets or retrieves transformation. Unselects all points.
Calls fcn repeatedly while mouse button is down.
FCN should take two arguments, the current x and y coordinates of the mouse. Should be called when button is already down. Sets or retrieves current acis label state. All three should be supplied for setting a new state. A list of the three properties is returned.