Clicking some sequence, say, double-right, lays down a help diagram showing
what each direction of the mouse does.  Moving outside the diagram exits
this mode and removes the diagram.  While in that mode, single clicks on
the mouse keys cycle through the menu when the cursor is in the neutral
area.  Clicking while cursor is in one of the item's sectors selects that
item.  

menu is laid out so that all choices are initially equidistant from the
cursor, so only direction is needed to choose one.  The diagram stays as
long as the button is held, while the cursor moves within it.  The
selection is indicated by the  sector
in which the cursor lies when the mouse button is released.

The output of the selection is the direction, perhaps

applications
------------

mouse menu for inputting numbers from circular scale (say, degrees).

time: press left to set hour hand, middle to set minute hand.