I found a thread on MSDN that shows how to add an item to the context menu of a winform title bar. Unfortunately it does not show how to register an event with the custom me
For a separator just add:
public const Int32 MF_SEPARATOR = 0x800;
and in Form_load:
InsertMenu(MenuHandle, 7, MF_BYPOSITION | MF_SEPARATOR, 0, string.Empty); // <-- Add a menu seperator