collision correction axis

[Kieren MacMillan]

Hi all,

Is there a way to control the axis along which a grob is pushed when a 
collision occurs?

In my "ScoreMarks" context (which sits above certain staves in a given system), 
I have rehearsal marks, tempo markings, and oversized time signatures. When two 
events happen at the same time (e.g., time signature change and a tempo 
marking), it stacks the items vertically; I would prefer for (e.g.) the 
rehearsal mark to move to the right instead.

Is this possible?

Thanks,
Kieren.