The next release has additional ways to use the keyboard, the mouse or both to toggle the dock's visibility.
The keyboard handling has been enhanced by allowing you to nominate a second key to be pressed, so that sequences such as "Ctrl D 1", "Ctrl D 2" etc., are now possible. Of course, single keystrokes (with or without) modifiers are still supported.
For mouse-centric users, the centre, X1 and X2 buttons are available with (new) or without keystroke modifiers (Ctrl, Alt, Shift & Win) and if one or more of those modifiers is selected, the left and right buttons become available also.
As for mousedown-pause-mouseup handling, well that could be highly dependant on how quickly the windows global message queue gets processed. Circle Dock's keyboard and mouse handlers do not simply trap events sent to that program, they trap all keyboard and mouse events system-wide.
I will investigate this to see if there's a clean way of implementing this without disturbing the existing handlers which are somewhat complex.