ZFP - Zooming of mouse drag function is not sync with mouse drag

Customer were using CWeb, and they use the zooming function by mouse drag.(Push scroll wheel and drag the mouse).(Push scroll wheel and drag the mouse).

It works also on ZFP, but the zoom behavior is not sync with mouse drag.

CWeb is sync, then zooming is stop if we stop dragging.

But ZFP is not sync, (The zooming speed is constantly same, so maybe it affect the drag distance) so sometime zooming is continue even if we stop the dragging.

As the result, they can not adjust the size which they want to be.