EditorUtility.DisplayPopupMenu  

static function DisplayPopupMenu (position : Rect, menuItemPath : String, command : MenuCommand) : void

Description

Displays a popup menu.

Menu is shown at position pos, generated from a submenu specified by menuItemPath using a MenuCommand as menu context.

// Shows the Assets menu when you right click on the contextRect Rectangle.

class EditorUtilityDisplayPopupMenu extends EditorWindow {
    function OnGUI () {
        var evt = Event.current;
        var contextRect = Rect(10,10,100,100);
        if(evt.type == EventType.ContextClick) {
            var mousePos = evt.mousePosition;
            if (contextRect.Contains (mousePos)) {
                EditorUtility.DisplayPopupMenu (Rect (mousePos.x,mousePos.y,0,0), "Assets/", null);
                evt.Use();
            }
        }
    }
}