pcmanfm is a very fast file manager
apparently it depends on the following configuration file (in order to better integrate with any existing themes...)
if you're like me with a minimal system...
nano /home/username/.gtkrc-2.0 gtk-icon-theme-name="GNOME"
Do the same for /home/username/.gtkrc-2.0-kde gtk-icon-theme-name="GNOME"
with those two lines you can effectively use pcmanfm without the silly popup