The spacing between the application icons, that I enter in the quicklauncher preferences dialog, is not persisted between sessions on Xubuntu (Ubuntu 14.04.2, 64bit; xfce4-panel 4.11.0-0ubuntu1; xfce4-quicklauncher-plugin 1.9.4-10ubuntu1). I always have to re-enter the spacing parameter in the quicklauncher preferences dialog when I log into Xubuntu again, even though the extra_spacing parameter in ~/.config/xfce4/panel/quicklauncher-11.rc already shows my preferred spacing (extra_spacing=22). I presume that this parameter is either not read or not read correctly when the xfce4-quicklauncher-plugin initializes.

This bug was also present on an earlier, 32bit, PC I had, with Xubuntu 14.04.0 installed. I can't reproduce the exact xfce4-panel and xfce4-quicklauncher-plugin versions, for that PC, anymore.