Did you actually test that? While the protocol works great in command line, it does not work within the context menu. I tried every wacky combination of quotes I could think of:
paintdotnet:%1
paintdotnet:"%1"
"paintdotnet:%1"
"paintdotnet":%1
"paintdotnet":"%1"
"paintdotnet:""%1"
"paintdotnet:'%1'"
"'paintdotnet':%1"
"'paintdotnet':'%1'"
"'paintdotnet:''%1'"
Even just a bare:
paintdotnet:
Still gives either "Windows cannot access the specified device, path or file. You may not have the appropriate permissions to access the item.", or "Which program do you want to use".
