I am working on a python addin for ArcGIS 10.2.2 and I would like to set the default path for the "file open" command to a user-specified location after a script tool executes. One of the functions that my addin performs is to launch a script tool that copies some .mxd's to a user-specified location. I would like to use that location as the default path, so users can access the other mxd's that were copied by the tool without having to navigate to that folder. I have used the comtypes module to get a reference to the current document, and it seems I can wrap any of the ArcObjects interfaces I will need. Is there a way to access the property that the Open command uses to open the explorer window? Any suggestions about where to start digging into ArcObjects would be appreciated.