As a matter of fact this door has never been the door of the gas chamber of Krema I.
Initially the building was used as an ammunition bunker. In 1941 it was transformed in order to be used as killing installation. A gas chambers and crematories were added as shown on this plan:
http://phdn.org/archives/holocaust-...sac/technique-and-operation/pressac0153.shtml
Once bigger installations have been build (Krema II and III) the building was refitted. Crematories were removed and the building was changed into an air-raids shelter, which included notably new separation wall inside what had been the gas chamber (see this plan:
http://phdn.org/archives/holocaust-...sac/technique-and-operation/pressac0156.shtml )
In 1948 the building was restored in its state of end 1942, but with some mistakes. Among others they did only rebuild two crematories (while there were three in 1941). Furthermore they destroyed one wall that was existing end of 1941 (shown in dashed lines on this plan:
http://phdn.org/archives/holocaust-...sac/technique-and-operation/pressac0159.shtml ). This was the original wall of the gas chamber in Krema I and the entrance (with the door of course) was open in that wall and not where your picture shows it.
This door on your picture has never been the door of any gas chamber. This is well documented and all people with a minimum knowledge of Auschwitz are perfectly aware of this. Only deniers continue to use this argument which has been debunked years ago.
And accurate information about this is provided to Auschwitz visitors (see this link:
http://www.phdn.org/negation/KremaI-chambreagaz-textepanneau.jpg ) so that the only conclusion that comes to mind when one reads that a person who went to Auschwitz tells again the story of wooded door with a glass panel is that this person is of bath faith.