Cell background has to be changed, if the cell doesn't contain formula.

I have tried implementing it in following ways

I have tried changing the cell back ground using Conditional formatting with
User Defined function(to check if cell has formula or value); but, adding
User Defined function degrades the performance of the template.
I have tried changing background by executing VSTO code on Range Change
event. But, undo stack is lost and user is unable to undo the changes
I also tried using Excel 4.0 macro..please see the implementation below..

You can use Excel 4 macro in a defined name formula to check if cell has a
formula, using you example
do insertnamedefine, in the source box put

=GET.CELL(6,Sheet1!$A1)

and in the name box type in something descriptive like

FormulaIs

click OK


Select A1:A3
with A1 as the active cell, do formatconditional formatting, select formula
is
and use

=LEFT(FormulaIs)="="

or in a pedagogic manner

=LEFT(FormulaIs,1)="="

you can actually leave out 1 if you just want one character

now click the format button and select format and click OK twice

But, I cannot use this method, because I get a security warning for Excel
4.0 macros when I open the template.


Is there any other way of checking if a cell contains formula in conditional
formatting?