Abstract: An in-line window structure for a transport vehicle is comprised of a rectangular frame in which a fixed pane is immovably secured. A displaceable pane is positionable adjacent the fixed pane in a common plane therewith. A lock interconnects sash members of the fixed and displaceable panes when positioned in a common plane. Guide tracks are provided by an elongated straight track section extending behind the fixed pane, and commuting track sections for guided displacement of the displaceable pane from the common plane to the straight track section and behind the fixed pane and substantially in alignment therewith whereby to create an opening in the rectangular frame to one side of the fixed pane. The lock is incorporated in a handle which, when squeezed, automatically retracts a latch bolt.