Hello, I've little question. How I can in KDE merge desktop. I mean that if someone window stick out beyond desktop to other desktop, it stick out part is visible on this second desktop. I try explain on picture.

now:
https://www.dropbox.com/s/h98s008pjnhrwfc/1-1.png
https://www.dropbox.com/s/xd14cxfcovuzz1p/1-2.png
I would like to was so:
https://www.dropbox.com/s/lvexjg1w8q10srs/1-3.png
https://www.dropbox.com/s/jhktkbtulw8n5s6/1-4.png

now:
https://www.dropbox.com/s/9xbn2y4mxo6vy72/2-1.png
https://www.dropbox.com/s/h6ii2jq79bmmbrs/2-2.png
I would like to was so:
https://www.dropbox.com/s/h2m0jsd3ggbpgwt/2-3.png
https://www.dropbox.com/s/5ledk6ec15o4vef/2-4.png

This is not possible. A window is only visible on the desktop it is on.

Once, as I was using ubuntu 9.10 with gnome it worked that way.

"It's not possible" = "The concept is not implemented in KWin"

There's always been the two concepts of VD as "rooms" (as in the original Xerox implementation) and "panning viewports on a huge desktop" - KDE (and afaics actually most X11 WMs) has ever followed the "room" approach.

For compiz there's (or has been) a plugin to follow the viewport approach and you could (meanwhile) write a kwin script to somewhat cause this behavior.

The viewport approach will conflict with the cube effect (a grid cannot be represented by a cube) and - correctly implemented - bleed shadows of maximized windows, but the biggest concern about it is that it will by design make titlebars conditionally inaccessible - thus it's usually disregarded as VD concept by WMs.