Horiz. position of semibreve and breve note changes with 'stem' direction

Context: today revision from github repo (82f1b1f) compiled and run under Ubuntu 11.10

Steps: Create a score and enter crochets, minims, semibreves and breves, some below the staff middle line (stem 'naturally' up) and some on or above the middle lines (stem 'naturally' down).

Result: breves and semibreves whose stem (if present!) would be down are displaced to the right (or vice versa?)

Screen shots:
Screen shots have been made with only one note per measure to make easier to see the note horizontal position (scores are attached).

Up to A's, barline-note distance for semibreves and breves is shorter than from B's on:

F chords and G chords are correctly aligned for crochets and minims, but for semibreves and breves, F's and A's are moved to the left and/or G's, B's and D's are moved to the right:

As this affects a basic rule of music engraving, I was about to rate it critical; finally I decided to keep it normal, but I think it to be rather important.

Note: is the code responsible for this behaviour located at lines 1487 - 1497 of function Chord:layout() in file libmscore/chord.cpp?

Thanks,

M.