MAcOSLib: Cocoa NSImageview doubleclick?

In order to make it easier to define the final sizes of some button controls, I use MacOSLib’s NSImageview Property. Everything fine so far, but it seems to me the implemented double click event never gets fired. I know I could skip around this with comparing the delta of the last click ticks to the ticks of the current click, but I wonder if I did something wrong. Is this event confirmed to fire correctly?