[Closed] Zoom-In the image in VFB

The task is to zoom-in the bitmap in the Virtual frame buffer. The code that I have so far is this:

(
	function MakeParam LoWord HiWord = 
	(
		bit.or (bit.shift HiWord 16) (bit.and LoWord 0xFFFF)
    )
	
	function MouseButtonClick pos viewHWND = 
	(
		WM_MOUSEHWHEEL = 0x020A
		pp = makeParam (pos.x as integer) (pos.y as integer)
		windows.postmessage viewHWND WM_MOUSEHWHEEL 0 pp
-- 		windows.postmessage viewHWND WM_MOUSEHWHEEL -1 pp
	)
	
	
	function GetVFBbuttons = 
	(				
		childArr = UIAccessor.getChildWindows 0
		maxVFB = undefined	
		stopLoop = false
		for chld in childArr while stopLoop == false do 
		(		
			dialogTitle = UIAccessor.getWindowText chld		
			if (matchpattern dialogTitle pattern:"*, frame * (*:*)") do 
			(		
				maxVFB = chld
				stopLoop = true
			)			
		)	
			
		maxVFB	
	)
	
	maxVFB = GetVFBbuttons()
	
	screenPos = [500,500]
	mouseButtonClick screenPos maxVFB
)
	

To test it just render some objects and while the VFB is visible execute the code.
It simulates mouse wheel rotation over the VFB window. On each rotation the zoom level is changed(level up or level down).
The problem is that this code actually performs zoom-out. When I use the same code(slightly modified) for the active viewport this
windows.postmessage viewHWND WM_MOUSEHWHEEL 0 pp
performs zoom-in
and this:
windows.postmessage viewHWND WM_MOUSEHWHEEL -1 pp
performs zoom-out.
But for the VFB both parameters(0 and -1) performs zoom-out.

Is there are any solution?