1. Load Nuclear Politics,  http://debategraph.org/Stream.aspx?nID=53836
You don't have to log in, and you can make sure that no other Debategraph tab is open.
2 Click on the Stream tab
3. Click on "Ralf Groetker" (who recently joined the map). This displays the map community. (so an alternative for step 3 is clicking on "Display the map community")
4. Click on "My Home map" (under Ralf Groetker). This loads (as expected) Ralf's personal map on the left side of the screen, but if you now click on the Details tab, you'll still find the details of Nuclear Politics and not the details about Ralf. If you click on some other node in Ralf's map, the map will change normally, but the Details, Context and Stream tabs will no longer behave as they should.

Note that if you do the same with David Price instead of Ralf, the bug will not appear.