Re: Double Click Capturing
You could have a timer. Start the timer in the releaseEvent handler and make sure the timeout is long enough to handle the double click first. Then, in the double click event handler you can stop the timer and prevent it from firing. If a double click handler is not triggered, the timer will timeout and call a slot of your choice, where you can handle the single click. This is of course a nasty hack, but has a chance to work.
Re: Double Click Capturing
You might want to take a look at Raymond Chen's blog post titled Logical consequences of the way Windows converts single-clicks into double-clicks where he describes the same technique Wysota does but makes some additional remarks on why it's a bad idea.