Control.ControlCollection.GetChildIndex Method (Control, Boolean)
Retrieves the index of the specified child control within the control collection, and optionally raises an exception if the specified control is not within the control collection.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
The control with an index value of zero is at the top of the z-order, and higher numbers are closer to the bottom. A return value of -1 is returned only when the throwException parameter is false.
Available since 1.1