I have laptop, android tablet and monitor and want to use tablet like monitor.

Using xrandr I can extend virtual screen to contain space for tablet screen and then share this part of virtual screen to network through vnc.
Even I can put there windows edge, but kde think that my desktop ends at border of external monitor so it's denied to pass mouse pointer to x11vnc part of desktop

Any ideas?

If it possible to create virtual monitor which place may be configured through kde settings, so I think problem will be resolved
But I found only way through xorg.conf(create dummy video card and combine with real display used xinerama),
it not useful for me because I need different configurations at home and at work

I try x2vnc and x2x, but they inconveniently in this task
Also I try synergy2, but I can't use mouse and keyboard because all my clicks in shared region of desktop responses as if I click on right edge of monitor.
I think: when kde see mouse click with coordinates out of desktop, kde changes it to coordinates on the corresponding edge of desktop