Otto,
Here you have it
http://wiki.fivetechsoft.com/doku.php?id=fivewin_resources_editor&rev=1252273224&do=diff
oCtrl:bLDblClick = { || msginfo( AllTrim( Str( GetWindowLong( oCtrl:hWnd, GWL_ID ) ) ))}
Here it works fine
nID := GetWindowLong( oCtrl:hWnd, GWL_ID )
msginfo( nID )