Adding item in listbox

Suppose I have a listbox, name it listbox1, containing 4 elements : A,
B, C, and D. There is another listbox, name it listbox2, whose value
will be subset of values of listbox.

For example, if user choose from listbox1 : A, B, and D then, the
values of listbox2 will be A, b, and D. Obviously I can do this by
"Listbox items transfer" procedure.

Now I want to be little bit tricky. Instead of showing A, B, D in
listbox2, I want to show A-B, and A-2*D.

Can anyone tell me how to do this type of job? Here I thought to use
listbox for doing that. Is there any other idea for doing the same?
Your help will be highly appreciated.

Thanks
:rolleye:




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volabos