It's time-saving to use the "func_group" function in GTK Radiant.
Example: Imagine you are building a hall with pillars consisting of many brushes. When moving these pillars you could select all the brushes manually and then move the pillar, over and over again for each pillar. When using func_group in GTK Radiant you only need to select one of the pillar's brushes and press a combination of keys to select all the brushes in the func_group entity.
First you select all the brushes of the pad you want to group.
Then you right mouse button click in any of the 2D views and select "func\func_group".
Deselect by pressing Esc. The lines of the pad on the grid are now in blue.
Select a brush from the func_group you just made.
To select all brushes press Ctrl+Alt+e (for GTK Radiant 1.5) or Ctrl+Alt+left mouse button click (for GTK Radiant 1.4).
Now you can move all the brushes without the need to click more than one brush.