[Chimera-users] launch behavior query

Hi, I have Chimera listed as the default app on my Mac to open MRC and PDB files. It used to be that if I double clicked on a pdb, and I had Chimera open, the pdb would open in that instance of chimera. Now, it always spawns a new instance of chimera. Is there any way to revert to the old behavior? Cheers Oli