[CMake] about generated Windows executable

[nico]

Hi,
first, i would like to thank you for this great tool...

i'm using cmake on macos 10.7.2, for my project cmake create osx bundle, 
windows executable, and very soon linux executable.
the windows executable is generated thanks to a cross mingw compiler.
the problem i'm facing is when i launch my program on windows, a dos 
shell like appears...
is there's a way to prevent that ?

also, but not very much important, can i use cpack in nsis way on the 
mac to create a windows installer.

best regards
nico