How do i check if an instance of the form already exists?

Im developing a plugin for Rhino, and when i run the command starting plugin i carries out the following. It creates a splash form, which has a timer on it, and after 2sec i loads another form.

If i by mistake click the plugin-icon again, it creates another instance of the spash form, which loads the plugin again.

How do i prevent this?

This is the code that makes the form.

public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
            {

                Splash Splash = new Splash();
                Splash.Show();

             开发者_Python百科   return IRhinoCommand.result.success;
            }

public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
{
    if (!Application.OpenForms.OfType<Splash>().Any())
    {
        new Thread(() => Application.Run(new Splash())).Start();
    }
    return IRhinoCommand.result.success;
}