I use gkrellm and have had no issues with it. I just did a zypper dup and after
a reboot gkrellm fails to start.

(gkrellm:9288): GdkPixbuf-WARNING **: 17:47:20.649: Error loading XPM image
loader: Unable to load image-loading module:
/usr/lib64/gdk-pixbuf-2.0/2.10.0/loaders/libpixbufloader-xpm.so:
/usr/lib64/gdk-pixbuf-2.0/2.10.0/loaders/libpixbufloader-xpm.so: cannot open
shared object file: No such file or directory

This message repeats a bunch of times and then gkrellm dumps core. I tried
looking at the core dump with gdb  but there is almost no info there, probably
i need a debug build of gkrellm

I think this is the main problem:
libpixbufloader-xpm.so is missing but not supplied by yast (or zypper) 
In the previous Tumbleweed version it was in
/usr/lib64/gdk-pixbuf-2.0/2.10.0/loaders/

This whole thing is repeatable across multiple PC's