" i dont even know what GTK is"
Gtk+ is a set of useful programming routines the many, many application use to create a GUI. Another popular GUI programming set is Qt3. KDE uses Qt3 and Gnome uses Gtk+. Since you installed KDE you also have Qt3 installed.
You need to install Gtk+ even though you do not have Gnome installed because many Gtk+ based applications will run just fine on KDE provided that the Gtk+ routines are available to them.
Be prepared. Create a LifeBoat CD.