lucky for you yesterday I figured out exaclty how this works

I'm going to comment the GarminCentrafuseHelperApps.reg to make it simple
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Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\GARMINCFMONITOR]
"left"="0"
"right"="0"
"top"="0"
"bottom"="0"
these 4 valuse define an area of the screen which forces gmpc to go to background, on MOUSEOVER event, not mouse click, only mouse over. In a touchscreen environment it's about the same thing, but with a mouse it's not
"zone2enable"="1"
"left2"="728"
"right2"="800"
"top2"="520"
"bottom2"="600"
it you set zone2enable=1, it enables another area of the screen with exactly the same function as the other. Mouse over it and garmin goes background.
"DEBUG"="0"
"TOOLTIPS"="0"
nothing useful here
"GarminNavigatorWindowSizePosition"="0,0,800,4 90"
this defines the area of the screen that gmpc will be using by default in normal use, covering the centrafuse main window and staying foreground until the mouseover event occours
"GarminNavigatorWindowSizePositionOSK"="0,0,800,45 0"
this defines the area this defines the area of the screen that gmpc will be using when the osk is active
"ActivateOSK"="0,0,700,45"
this defines the area of the screen where you have to CLICK to make the OSK visible. Here you need a click not a mouseover event
"APPPATH"="c:\\GarminMobilePC\\Que.exe"
"APPNAME"="Garmin Mobile PC"
"APPWORKINGDIR"="c:\\GarminMobilePC"
I think this explains itself well
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As you can see I defined the first mouseover zone to ZERO to avoid the mouseover on the top of the window, I also defined zone2 with the coordinates of the CF EXIT button on the lower right corner of the screen, and in CF configuration I forced the event on click of this button to NONE. I also customized the ActivateOSK area expanding it on the top border of the screen avoiding the top righe angle; doing this allows me to close and check satellite coverng without mess with the OSK
I hope I explained it well, if you have problems just let me know