I am trying to subclass NSSlider to create a control called a jog dial. Basically what I need is a slider which always starts at the middle and when it is moved to the left or right it will send notifications every so often (determined by an attribute one can set) informing its container of its current value, then when you let you go of the knob, it will return to the middle. I was hoping to implement the functionality to return the slider to the middle and stop sending notifications in the mouseUp event of the slider but it seems that for some reason apple disables the MouseUp event after a mouseDown event on the slider and handles all the slider functionality at a lower level. Is there anyway I can get the mouseUp event back? If not can anyone suggest a reasonable workaround?
Whenever you notice that a superclass's implementation of mouseDragged: or mouseUp: is not getting called, it's most likely because the class's implementation of mouseDown: enters a tracking loop. This is certainly true of many NSControl subclasses including NSSlider.
A better way to detect a mouse up is to subclass the cell and override the appropriate tracking method. In this case, you probably want - (void)stopTracking:(NSPoint)lastPoint at:(NSPoint)stopPoint inView:(NSView *)controlView mouseIsUp:(BOOL)flag, but the startTracking: and continueTracking: variants might prove useful as well for what you're trying to do.