binary vs. build behavioral difference

[Mithat Konar]

I am trying to build IceCat on Ubuntu 9.10 (i686). My goal is to --enable-cairo 
to get better font rendering, however I've encountered a bit of a snag I'd like 
to solve.

Using the latest release (3.6.4) and the .mozconfig exactly delivered in the 
tarball (i.e., no --enable-cairo modifications), I am noticing a difference in 
behavior between the IceCat-i686 binary and what I build locally.

The behavioral difference regards opening files after they have been 
downloaded. 
When I right-click on an entry in the Downloads window, with the binary version 
I am asked to specify a file manager and given options to make it permanent, 
etc. When I do the same with my locally compiled version, it automatically 
opens 
in Nautilus. This happens with virgin ~/.gnuzilla files.

The behavior of the binary is what I want, but I have no idea why it's not 
happening with the local build.

Help?

-M