Actually, managed to find this thread (On Mouse Button Double Click Bug - #21 by anonymous_user_136e418c).
The solution seems to be to swap out On Mouse Button Down with On Preview Mouse Button Down. Very odd, but looks like the workaround.
Actually, managed to find this thread (On Mouse Button Double Click Bug - #21 by anonymous_user_136e418c).
The solution seems to be to swap out On Mouse Button Down with On Preview Mouse Button Down. Very odd, but looks like the workaround.