Color MDI Form

If we want to change background color of a form: we usually do like this:

 Form1.Color := clYellow;

However, if a Form's FormStyle is fsMDIForm, change the color at runtime will not update immediately not until the form has been fully repaint or resize. Invoke TForm.Refresh, TForm.Update, TForm.Repaint will not update the color as well. To make the a MDI form update the background color immediately, we may do this:

 Form1.Color := clYellow;
 Windows.InvalidateRect(Form1.ClientHandle, nil, True);