Use ShowMainForm to control whether and when the application shows its main form.
The default value of true is set in the constructor. When ShowMainForm is true the main window shows automatically when the application starts. The MainForm property specifies which form is the main form.
To hide the main form at startup, set ShowMainForm to false in the main project file before the call to Application->Run. Make sure that the Visible property of the form is also false.