Opening saved files in Rhino 6

I am getting used to Rhino 6 and find it a great program, However I dont use Rhino enough to get proficient in 6, and revert to using 4. Plus 6 does things to my older files that would take me a long time to fix so I keep 4 alive on my computer.
I would like to click on the files icon and have the system know if the .3dm file is a 4 or a 6 and open it in the right program.
Right now they default to opening in 4 and I have to ‘open with’ to open files in 6.
Other than making 6 the default and reversing the above step I havent figured this one out.
Any ideas??

I don’t know about the system thing but with this script you can make a button in rhino 6 to convert all the files you want into v4 again without opening them individually:

paste the below text inside a new button:

! _-RunPythonScript (

import rhinoscriptsyntax as rs
import os

def BatchSaveAsV4():
#Get folders
folder = rs.BrowseForFolder(“Select folder to process”)
if not folder: return

saveFolder=rs.BrowseForFolder("Select folder to save files")
if not saveFolder: return

found = False ; counter=0 ; suffix="-V4"
#Find Rhino files in the folder
for filename in os.listdir(folder):
    if filename.endswith(".3dm"):
        found = True ; counter+=1
        #Close the current file
        rs.Command("_-New _None",False)
        #Open file to convert
        rs.Command ("_-Open " + chr(34) + fullpath + chr(34), False)
        #Save file as a V4 file with suffix            
        comm="_-SaveAs _Version=4 "
        comm+="_SaveSmall=_Yes _GeometryOnly=_No _SavePlugInData=_Yes "
        rs.Command(comm + chr(34) + savepath + suffix + ".3dm" + chr(34), False)
if not found:
    print "No Rhino files found in selected folder!"
    print "{} files converted to V4 format".format(counter)
#open a blank document to finish
rs.Command("_-New _None",False)



That may come in handy in the future.
My quandary is a bit simpler, on a one for one basis.
When I click on an rhino file icon to open it, my default is set to use Rhino 4.
I dont see anyway to distinguish a Rhino 6 from a 4 file, so that the file opens in the version it was created in.

Hi Bobmo - can you be more specific? Do you have an example?


Well Thanks Pascal for asking.
When I first got Rhino 6 and loaded my Version 4 files, all the text in my drawings was blown out of proportion…HUGELY. And I never went back after that.
So as I tried to verify the problem today I opened three different files in 6 and 4 and they all look the same!
Looks like I can retire Version 4, and my problem has been solved.