In the construction of window and door assemblies, it is common to use insulated glass panel units of the general type disclosed in U.S. Pat. Nos. 5,003,747 and 6,675,537 which issued to or are owned by the assignee of the present invention. Usually, the insulated glass units include two parallel spaced rectangular glass panels having peripheral edge portions which receive a rectangular spacer frame. The edge portions and spacer frame are bonded and sealed together by a bonding compound such as a butyl rubber compound or a similar bonding material surrounding the spacer frame. The insulated glass panel unit is assembled into a surrounding rectangular sash frame and is retained by glazing members or beads. Preferably the sash frame and glazing beads are formed from extrusions of plastics material such as polyvinyl chloride (PVC). Such insulated glass panel units are commonly used in fixed window assemblies such as picture windows, single hung windows, sliding windows, bow and bay windows and sliding and swinging patio door assemblies such as disclosed, for example, in U.S. Pat. No. 6,318,036 which issued to the assignee of the present invention.
In insulated glass panel units as described above, it is common for the outer edges of the glass panels to be exposed and unprotected during handling and shipping or be covered by a thin layer of the bonding and sealing compound. When the outer edges of the glass panels are relatively unprotected, insulated glass panel units must be carefully handled and carefully protected during shipping. Also, when the edge surfaces of the glass panels are exposed, the personnel handling the insulated glass panel units need to wear gloves in order to avoid cutting their fingers or receiving glass splinters. It is also desirable for a fixed window assembly, such as a picture window assembly, to provide for conveniently removing the insulated glass panel unit in the event of glass breakage or damage or moisture seeps into the space between the glass panels and results in etching the inner surfaces of the glass panels.