uses Registry;

function RegisterFileTypeCommand(fileExtension, menuItemText, target: string) : boolean;
var
  reg: TRegistry;
  fileType: string;
begin
  result := false;
  reg := TRegistry.Create;
  with reg do
  try
    RootKey := HKEY_CLASSES_ROOT;
    if OpenKey('.' + fileExtension, True) then
    begin
      fileType := ReadString('') ;
      if fileType = '' then
      begin
        fileType := fileExtension + 'file';
        WriteString('', fileType) ;
      end;
      CloseKey;
      if OpenKey(fileType + '/shell/' + menuItemText + '/command', True) then
      begin
        WriteString('', target + ' "%1"') ;
        CloseKey;
        result := true;
      end;
    end;
  finally
    Free;
  end;
end;

function UnRegisterFileTypeCommand(fileExtension, menuItemText: string) : boolean;
var
  reg: TRegistry;
  fileType: string;
begin
  result := false;
  reg := TRegistry.Create;
  with reg do
  try
    RootKey := HKEY_CLASSES_ROOT;
    if OpenKey('.' + fileExtension, True) then
    begin
      fileType := ReadString('') ;
      CloseKey;
    end;
    if OpenKey(fileType + '/shell', True) then
    begin
      DeleteKey(menuItemText) ;
      CloseKey;
      result := true;
    end;
  finally
    Free;
  end;
end;