Not sure if it is mentioned anywhere, but you can use Creator so that you open the project normally on the pc and compile on pc as usual.
And only when you cross-compile, you open MADDE, run a 'make clean' and build for the N900. A bit of a trick, but it works for me.

I guess we kind of surprised the Qt Creator folks a bit with the timing too :-) Let's see when they can come up with a Creator version for MADDE.