Understanding Windows Forms layout and Dock behavior.
When laying out forms, the behavior of docking (& anchoring?) depends on the “depth” of the control. An “in-front” control will respect the boundaries of controls behind it when docking. An “in-back” control will ignore controls in front of it when docking.
There doesn’t appear to be an explicit way to tell what the depth of a control is.
The context menu has move forward/backward commands on it.
New controls are in-front of old controls.