sliding glass door security...
I guese when you say secure the door you mean: security wise?
If yes then:
C clamps or a screw run through the track can prevent or deter someone from lifting the door out of the track to break in.
A broom stick cut to proper length can be laid on the floor between inside door and wall to keep it from being opened. There is a type of bar that can be attached to the inside door (swinging portion of bar) and the other side of the bar is shaped like a U so it slides over or into the handle of the of the outside door this will prevent both doors from being moved.
Locks are also available which attach to the floor and have a pin which engages the door.
An alarm system is a good deterent especially if you place a sticker which says you have one on the door you want to secure.
Last edited by eric s; 11-25-2006 at 10:20 PM.
Reason: more advice