I would like to add an unbound checkbox to my form that will be either
checked or unchecked based on the values of two bound controls.   For
example, if the value of one control is less than 90% of the other
control, I would like the checkbox to be checked, otherwise unchecked.

I can use an expression box with conditional formatting to display in a
certain fashion (i.e bold, different color, etc.) according to the
values of other controls, however I am after some form of graphical
representation that will be easily viewed when the document is printed
on a monochrome printer.

Any help would be appreciated.