Hi, need to write this value : "C:\Ba\Ba.exe" "-E" "%1" in the Registry. the function below almost works except for the Quotes !!! this is important so -E is in $1 and %1 in $2... setRegistry( "HKEY_CLASSES_ROOT\BioArchimed\shell\open\command\", "C:\Ba\Ba.exe -E %1" ) Any clue Best regards, thierry