Adding extra voice at arbitrary position impossible

OS X 10.6.2 - r.2674
Not sure if this is a bug or a feature request, but anyway. Likewise, it's not clear whether bug reports are preferably reported in the forum or on the tracker.

open Moussorgsky demo file
enter note entry mode
note in voice 1 can be added everywhere
notes in other voices can only be added at beginning of measures or at places where that voice is already present

It is thus impossible to add a second voice (like in measure 3) later on without putting in rests from the beginning of the measure (and optionally deleting them or making them invisible afterwards).