Hello there !
i'm having the same problem with version 1.6.2 just upgraded, with iceweasel browser running on debian.
It's possible to modifiy a date event or task as dragging is working, but as the end of the month, it's not possible anymore !!
For me it does'nt work even in the task section...
Niels : did you solve the problem ?
Vladlen : i don(t understand well your modification and don't find the same code in line 390 (but i'm running with version 1.6.2)....
If someone has a solution or an idea...
Bye bye
Marco