Tk_QueueWindowEvent places a window event on Tcl's internal event queue for eventual servicing. It creates a Tcl_Event structure, copies the event into that structure, and calls Tcl_QueueEvent to add the event to the queue. When the event is eventually removed from the queue it is processed just like all window events.
When multiple motion events are received for the same window in rapid succession, they are collapsed by default. This behavior can be controlled with Tk_CollapseMotionEvents. Tk_CollapseMotionEvents always returns the previous value for collapse behavior on the display.
The position argument to Tk_QueueWindowEvent has the same significance as for Tcl_QueueEvent; see the documentation for Tcl_QueueEvent for details.