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You are an expert at summarizing long articles. Proceed to summarize the following text: 
RELATED APPLICATION  
       [0001]    This application claims the benefit of the filing date under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 60/429,811, filed Nov. 27, 2002, the entire contents of which is incorporated herein by reference. 
     
    
     
       BACKGROUND  
         [0002]    The present invention relates generally to a window assembly. More specifically, the invention relates to a window guard to protect an edge in an opening of a window.  
           [0003]    A primary function of sliding window assemblies in vehicles is to provide ventilation for, e.g., the passenger compartment of the vehicle equipped with such an assembly. However, it is not uncommon for users to take advantage of the open window as a pass through for supporting lengthy cargo, thereby minimizing rearward extension of the cargo, e.g., into and/or beyond the bed of a truck having a backlight equipped with such a sliding window assembly. The force exerted by resting cargo on the exposed edge of the window causes abrasion and/or impact which may be a cause for concern.  
           [0004]    While the primary functional purpose of such a sliding window assembly in a vehicle is primarily intended for ventilation, it is not uncommon for users to take advantage of the window as a pass-thru opening for supporting lengthy cargo and thereby minimize rearward extension of the cargo outside the vehicle. The downward force exerted by resting such cargo on the exposed edge of the window opening should, in most cases, not be of major concern by itself, since the compressive strength of glass is generally quite good. However, lateral forces (fore &amp; aft), abrasion, and/or impact forces resulting from such cargo resting on the glass could be of concern.  
           [0005]    From the above, it is seen that there exists a need for protection of certain exposed edges in a window opening.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    In overcoming the above mentioned and other drawbacks, the present invention provides a window assembly, such as the slider backlight assembly commonly found on pick-up truck vehicles, having a fixed window with an opening, a slidable panel that slides relative to the fixed window to cover or expose the opening in the fixed window, and a covering to protect the lower edge of the window opening.  
           [0007]    The covering may be a protective sheet attached at one end to a lower member or portion of the window assembly. The other end remains unattached so as to create a flexible flap of material. When needed, the protective cover is simply placed over the exposed bottom edge of the opening to protect the edge from damage by objects resting on the edge, and when not in use the cover is allowed to hang freely or otherwise fastened out of the way below the window opening. The protective material could be suitably colored and textured to coordinate with adjacent interior trim materials. The covering is a flexible, durable sheet.  
           [0008]    The fixed end of the covering may be attached to the interior or exterior of the fixed window with a suitable connection means. Various attachment means, both permanent and releasable, can be used to secure the cover in place. The cover may be a substantially U-shaped clip that covers the edge in a removable manner.  
           [0009]    Further features and advantages will become apparent from the detailed description and from the claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The accompanying drawings, incorporated in and forming a part of the specification, illustrate several aspects of the present invention. The components in the figures are not necessarily to scale, emphasis instead being placed on illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the views. In the drawings:  
         [0011]    [0011]FIG. 1A is a back view of a sliding window assembly in an open position with a protective edge cover flap in accordance with an embodiment of the invention.  
         [0012]    [0012]FIG. 1B is a perspective view of a portion of the sliding window assembly.  
         [0013]    [0013]FIG. 2 is a perspective view of a portion of a sliding window assembly in an open position with a protective edge cover flap in accordance with another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0014]    [0014]FIGS. 1A and 1B depicts a sliding window assembly  10  with a fixed panel  12  and a slideable panel  14 . In one example, the panels  12  and  14  are both of glass and are used as part of the backlight assembly of a vehicle, e.g., a pickup truck. Alternatively, either panel  12  or  14  or both can be made from a plastic. In operation, the slideable panel  14  slides back and forth relative to the fixed panel  12  along a pair of rails  13  so that a user, such as the driver or passenger, can move the panel  14  between an open position and a closed position.  
         [0015]    In accordance with an embodiment of the invention, the window assembly  10  is also equipped with a protective edge cover  16  placed over an otherwise exposed edge  18  of an opening  20  in the fixed panel  12 . The edge cover  16  can be a detachable. In the embodiment illustrated in FIGS. 1A and 1B, the edge cover  16  is a “U”-shaped clip of rubber (or some other suitable durable material) that fits snugly over the edge  18 . Thus, the U-shaped cover  16  can simply be inserted over the edge  18  of the panel  12 , and thereby isolate or insulate the exposed edge  18  of the panel  12  from direct contact with cargo that might come to rest on the edge of the glass when the sliding panel  14  is in the open position. When the protective function of the cover  16  is not desired, the user removes the cover  16  by simply pulling the cover  16  away from the edge  18 , and the user can then move the sliding panel  14  to the closed position and lock the sliding panel in place with a pair of latches  15  that mate with a pair of attachments mechanisms  17  on the panel  12 .  
         [0016]    In its closed position, the slideable panel  14  covers the opening  20  in the fixed panel  12 . In its open position, the slideable panel is moved to the side to uncover the opening  20 . A user may then place cargo in the bed of the truck such that the cargo extends through the opening  20  into the cab of the truck and rests on top of the cover  16 . As mentioned above, the cover  16  functions as a protective cover for the lower edge  18  of the opening  20 . Accordingly, the edge  18  is protected from impact forces and abrasion from the cargo extending through the opening  20 . Thus, the user can place cargo on the edge  18 , for example, the lower edge of an opening in a sliding glass backlight assembly of a pickup truck, without concern for damaging the panel  12 .  
         [0017]    Referring now to FIG. 2, the cover  16  can be a protective sheet integrated into the design of the window assembly  10 . In this configuration, the cover  16  cannot become separated and lost or displaced.  
         [0018]    The cover  16  can be equipped with attachment features, for example, protrusions or snaps, which mate with attachment features formed on the fixed panel  12  or on the support structure in which the fixed panel  12  is mounted.  
         [0019]    The attachment features of the cover  16  are releasable from those on the fixed panel  12  or the nearby support structure of the cab in which the fixed panel is mounted. The attachment features can be configured for attaching the cover  16  either to the inside or outside of the fixed panel  20  or to both sides.  
         [0020]    In one implementation, the cover  16  has one end  22  coupled, for example, to the fixed panel  12  or the support structure for the fixed panel  12  by a hinge, adhesive, screw, or other suitable fastening mechanism  23 . The other end  24  of the cover  16  is equipped with a releasable fastening feature  26 , for example, a snap, hook and loop fastener, latch, or Velcro and the panel  12  or support structure is equipped with a corresponding fastener feature  28  located on the opposite side of the panel  12  from the fastening mechanism  23 . The fastener feature  28  mates with the fastening feature  26  in a releasable manner.  
         [0021]    To use the cover  16 , the user pulls the end  24  of the cover  16  and extends it through the opening  20  to cover the edge  18 . The user then secures the fastening features  26  with the respective fastening features  28  to hold the cover  16  in place.  
         [0022]    The implementation shown in FIG. 2 can be configured with the fixed end  22  coupled either to the outside or inside of the panel  12 . Thus, in certain arrangements, the protective edge cover flap  16  can be pulled from outside the cab, and in other arrangements, the cover  16  is pushed from inside the cab through the opening  20 .  
         [0023]    While the above description contains specificities, these should not be construed as limitations on the scope of the invention, but merely as examples of the presently preferred embodiments. Other variations are possible within the teachings of the invention. For example, the protective material of the cover  16  can be made from polyurethane, or polyvinyl and Kevlar, or any other suitable abrasion resistant material. The cover  16  can have any suitable thickness that isolates impact forces from being imparted on the bottom edge of the panel by the cargo. Moreover, the protective material can be suitably colored and textured to coordinate with passenger compartment trim materials.

Summary:
The present invention provides a window assembly having a fixed window with an opening, a slidable panel that slides relative to the fixed window to cover or expose the opening in the fixed window, and a covering to protect the lower edge of the window opening.