WaitMouseUp
WaitMouseUp Test mouse still down and discard mouseUp event
#include <Events.h> Event Manager
returns Is button still down since last mouseDown?
WaitMouseUp is identical to StillDown (it checks if the mouse button has
been continuously pressed since the most recent mouseDown event) except that
when the mouseUp event occurs, it is removed automatically from the event
queue.
Returns: a Boolean value reporting activity since the most recent mouseDown.
It is one of:
FALSE button is up or there are one or more mouse events pending
in the queue. It is not "still down".
TRUE button is down and it has not been released since the most
recent mouseDown. It is "still down".

Notes: WaitMouseUp simplifies drag operations without complicating the test
for double clicks. See GetDblTime.
See StillDown for an example of usage.