Comment 4 for bug 782111

According to this report http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=640473#10 it looks like
mootools.js file failed to load. Make sure it is present in "res" subfolder in midori instalation folder.
Speed dial uses a tiny bit of mootools in add function so it fails here. Strangely in this bugreport path misses
/res/ part so maybe it was not packaged properly. Should be midori/res/mootools.js

There also could be a hard to trace bug which happens sometimes.
Resource files just fail to load altogether (close and edit icons would not load as well as js file).
Refreshing speeddial page helps for the most part if that is the case.