Exporting to MIDI doesn't respect note length value

i'm using mscore from git d6d0b1a on kxstudio 12.04.3

The problem is musescore doesn't export the good note lenght value when I use export to MIDI file.

to reproduce :
1- create a new score (piano in my case)
2- Enter some chords with MIDI keyboard (for example half-note half-note whole-note chord)
3- export as midi
4- open the midi file in mscore (or any other midi software)
5- it results in shorter value than entered one (dotted quarter note dotted quarter note half-note linked with a dotted eight-note)

Let me know if you need more informations.