Compilation error when building demo vala application

[Philip Van Hoof <spam pvanhoof be>]

make[3]: Leaving directory
`/home/pvanhoof/repos/tinymail/ntr/tests/c-demo'
Making all in vala-demo
make[3]: Entering directory
`/home/pvanhoof/repos/tinymail/ntr/tests/vala-demo'
/opt/vala/bin/valac --vapidir ../../bindings/vala --pkg
libtinymail-gnome-desktop-1.0 --basedir ../.. tinymail-vala-test.vala
/home/pvanhoof/repos/tinymail/ntr/tests/vala-demo/tinymail-vala-test.vala:105.4-105.23: error: Argument 1: Cannot convert from `Tny.ValaMailWindow.on_refresh_folder' to `Tny.FolderCallback'
Compilation failed: 1 error(s), 0 warning(s)
make[3]: *** [tinymail-vala-test.vala.stamp] Error 1
make[3]: Leaving directory
`/home/pvanhoof/repos/tinymail/ntr/tests/vala-demo'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/home/pvanhoof/repos/tinymail/ntr/tests'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/pvanhoof/repos/tinymail/ntr'
make: *** [all] Error 2
pvanhoof schtrumpf:~/repos/tinymail/ntr$ 

-- 
Philip Van Hoof, freelance software developer
home: me at pvanhoof dot be 
gnome: pvanhoof at gnome dot org 
http://pvanhoof.be/blog
http://codeminded.be