Returns a list whose elements are the x and y coordinates of the point along the centerline of the trough that corresponds to value . If value is omitted then the scale's current value is used. If x and y are omitted, returns the current value of the scale. If the point isn't over one of these elements, an empty string is returned. This command is invoked to change the current value of the scale, and hence the position at which the slider is displayed.
Value gives the new value for the scale.
The command has no effect if the scale is disabled. Where the behavior is different for vertical and horizontal scales, the horizontal behavior is described in parentheses. If the button is held down, the action auto-repeats. If button 1 is pressed over the slider, the slider can be dragged with the mouse. If the mouse is dragged with button 2 down, the scale's value changes with the drag.