Minimise the active window.
Assuming the default menus are available, use the Window menu to switch between forms/windows.
“To minimize suffering and to maximize security were natural and proper ends of society and Caesar. But then they became the only ends, somehow, and the only basis of law — a perversion. Inevitably, then, in seeking only them, we found only their opposites: maximum suffering and minimum security” ~ Walter M. Miller, Jr.
Maximize - Enlarge the active window
Restore - Restore a maximized or minimized window.