I don't know the answer to your question, but I have the same problem compiling k3b. From my search, it appears that xlib_pics has to do with some dependence of kde development packages on xfre86 version 4.2.1, while knoppix comes with version 4.3.0. If you open synaptic and look at the description of xlibs_pic, it says it is a dummy package to deal with unmet dependencies in kde development packages. If anyone knows how to compile kde packages on knoppix, please reply!