In Cocoa, it is pretty easy to use an NSButton that creates a drop down menu. One of the key-tricks to making it appear to be an NSPopUpButton is to set the [NSCell sendActionOn:]. Generally, menus are displayed on mouse down, not up. Normally, the action for a button is sent on mouse up. To get around this, you can simply access the cell of your button and tell it to send the action on mouse down:
[[mybutton cell] sendActionOn:NSLeftMouseDownMask];
Cool!
