(Information and examples taken from the DroidScript documentation)

app.ShowProgress(text, options);

The ShowProgress method shows a popup progress window with a spinning animation and an optional message. This window will remain visible until app.HideProgress() is called.

 app.ShowProgress( text );

See also HideProgress

function OnStart()
{
  app.ShowProgress( "Loading..." );
  setTimeout( "app.HideProgress()", 3000 );
}