Playback and hide-see button

Hi,

When unig musesounds and playing a part with at least two instruments, hiding one of the instruments during playback causes a weird freeze for a few seconds and then the playback continues but no sound is emited.

This behaviour disapears when using the musescore soundfont.

Also when pressing space to pause the playback after this bug occurs, all the misse sounds are emited at the same time at a very low volume.

Y.