My original intent, back in 2007, was to be able to detect/determine the (low-level) bin numbers (the BinNr.:x at the end) to use for some older software that directly drives the printers with PCL5/PCL6 code and needs to select the correct numbers in the PCL code it sends. I had been testing with an old LJ4Plus that had an extra tray mounted underneath the main tray, and all was simple/well.
Eventually it turned out that the drivers used by the more modern (both HP and other brands) printers reported totally different numbers from the actually required PCL-code numbers
Though the list of possible trays was useful in some situations, this was still one of the reasons this project was shelved back then, as I couldn't find more accurate data
To be able to match possible paper trays, as gathered from the printer driver, and what's actually installed in the printer, I (have to) query Windows components. I (currently) don't intend to try and query the printers directly to retrieve that information, as that would be a project of several years, just to acquire the knowledge of retrieving it from all the printer brands available. (What are standards good for?)
Seeing your LJ2100, and the totally different (read: 'lack of' for Win7) information available on XP and Windows 7, I don't have much hope for better information from a lot of other drivers.
If you need/want the information on the paper sizes, I can try to squeeze that info in the view, though atm, I'm unsure I can directly match it to the tray at hand.
I'll release 188.8.131.52 first with an added bin-detection method.