Setting up a VNC server with KDE4 is a real challenge. The lack of support for the RENDER extension makes most qt4 applications unusable as shown by this screenshot:
And, the RENDER extension is not implemented by the VNC server as shown below:
Most solutions I have seen required that VNC is replaced by other solutions such as NX implementations (for example FreeNX). This is not an actual solution if you really requires a VNC server. As an example, I am using an Axel M75E Thin Terminal. Those sort of terminals offer a quite good solution for quiet, very thin graphical terminal. But it actually requires a VNC server. Fortunately, there is at least one VNC server implementation that implements the X RENDER extension: TigerVNC. By the way, it is available into the Portage Gentoo tree, so installing it is painless: emerge tigervnc. It works pretty well as shown by those screenshots:
And as suspected, the X RENDER extension is implemented by TigerVNC:

The VNC server implementations that do not implement the X RENDER implementation and that are therefore unsuitable for qt4 applications (including the whole KDE4) are:


