Palette Editor window is divided into multiple groups, and every group consists of several subgroups. For example, JSF consists of Core, Facelets, HTML:
By default the Palette is represented in Web Development Perspective with four groups. If you can't see it, select Window > Show View Other... > JBoos Tools Web > JBoss Tools Palette from the menu bar.
By using Show/Hide button you can add any predefined group of tag libraries. It's also possible to create your own group.