I represent control for scrolling using a scrollBar. I am a MouseMenuController that creates a scrollBar, rather than menus. My subclasses add the button menus. I keep control as long as the cursor is inside the view or the scrollBar area.

A scrollBar is a rectangular area representing the length of the information being viewed. It contains an inner rectangle whose top y-coordinate represents the relative position of the information visible on the screen with respect to all of the information, and whose size represents the relative amount of that information visible on the screen. The user controls which part of the information is visible by pressing the red button. If the cursor is to the right of the inner rectangle, the window onto the visible information moves upward, if the cursor is to the left, the window moves downward, and if the cursor is inside, the inner rectangle is grabbed and moved to a desired position.

	control defaults
	controlActivity isControlActive isControlWanted normalActivity

	cursor
	changeCursor: markerContainsCursor menuBarContainsCursor scrollBarContainsCursor

	initialize-release
	initialize

	marker adjustment
	computeMarkerRegion markerDelta markerRegion: moveMarker moveMarker:anchorMarker: moveMarkerTo:

	private
	scrollAbsolute scrollDown scrollUp

	scrolling
	anyButtonActivity downLine scroll scrollAmount scrollByKeyboard scrollView scrollView: scrollViewDown scrollViewUp upDownLine upLine viewDelta yellowLine

	basic control sequence	top
	controlInitialize Recompute scroll bars. Save underlying image unless it is already saved.
	controlTerminate Provide a place in the standard control sequence for terminating the receiver (taking into account the current state of its model and view). It should be redefined in subclasses to perform some specific action.

	control defaults	top
	controlActivity Refer to the comment in Controller|controlActivity.
	isControlActive In contrast to class Controller, only blue button but not yellow button events will end the receiver's control loop.
	isControlWanted Answer whether the cursor is inside the inset display box (see View|insetDisplayBox) of the receiver's view. It is sent by Controller|controlNextLevel in order to determine whether or not control should be passed to this receiver from the Controller of the superView of this receiver's view.
	normalActivity

	cursor	top
	changeCursor: The current cursor should be set to be aCursor.
	markerContainsCursor Answer whether the gray area inside the scroll bar area contains the cursor.
	menuBarContainsCursor Answer whether the cursor is anywhere within the menu bar area.
	scrollBarContainsCursor Answer whether the cursor is anywhere within the scroll bar area.

	initialize-release	top
	initialize Initialize the state of the receiver. Subclasses should include 'super initialize' when redefining this message to insure proper initialization.

	marker adjustment	top
	computeMarkerRegion Answer the rectangular area in which the gray area of the scroll bar should be displayed.
	markerDelta
	markerRegion: Set the area defined by aRectangle as the marker. Fill it with gray tone.
	moveMarker The view window has changed. Update the marker.
	moveMarker:anchorMarker: Update the marker so that is is translated by an amount corresponding to a distance of anInteger, constrained within the boundaries of the scroll bar. If anchorMarker ~= nil, display the border around the area where the marker first went down.
	moveMarkerTo: Same as markerRegion: aRectangle; moveMarker, except a no-op if the marker would not move.

	private	top
	scrollAbsolute
	scrollDown
	scrollUp

	scrolling	top
	anyButtonActivity deal with red button down in scrollBar beyond yellowLine
	downLine if cursor before downLine, display down cursor and scroll down on button down
	scroll Check to see whether the user wishes to jump, scroll up, or scroll down.
	scrollAmount Answer the number of bits of y-coordinate should be scrolled. This is a default determination based on the view's preset display transformation.
	scrollByKeyboard
	scrollView The scroll bar jump method was used so that the view should be updated to correspond to the location of the scroll bar gray area. Return true only if scrolling took place.
	scrollView: Tell the reciever's view to scroll by anInteger amount. Return true only if scrolling actually resulted.
	scrollViewDown Scroll the receiver's view down the default amount. Return true only if scrolling actually took place.
	scrollViewUp Scroll the receiver's view up the default amount. Return true only if scrolling actually took place.
	upDownLine Check to see whether the user wishes to jump, scroll up, or scroll down.
	upLine if cursor beyond upLine, display up cursor and scroll up on button down
	viewDelta Answer an integer that indicates how much the view should be scrolled. The scroll bar has been moved and now the view must be so the amount to scroll is computed as a ratio of the current scroll bar position.
	yellowLine Check to see whether the user wishes to jump, scroll up, or scroll down.