Web Compatibility Support • www.bahn.de/buchung isn't working—or is it?

The Deutsche Bahn website is always a source of problems. In recent weeks, the timetable search function www.bahn.de/buchung/start?intern=1 has stopped working with Palemoon because the displayed options couldn't be modified: When you click for example on the “Hinfahrt ändern” section, an overlay with a calendar should open. In Palemoon, the area is outlined in blue and the rest of the page is dimmed to gray.

So I tried out the new version to see if anything had changed. Unfortunately, nothing had changed in the standard version — but strangely enough, it was working on one computer!

To figure out what the difference was, I disabled all the add-ons in this installation. The calendar still loads. Only in safe mode it did not. A comparison of the modified entries in about:config did not provide any clues. The only likely explanation: The general.useragent.compatMode.firefox setting was set to “false” on the Palemoon that was working, and to “true” on the other computer (as is default). Unfortunately, I can't verify this, because for some reason, it seems that changes no longer can be made to this particular entry — neither double-clicking nor using the context menu works to change the value. So how do I get Palemoon to display the Deutsche Bahn website correctly? Apparently, it’s capable of doing so.