This thread contains some suggestions:
http://groups.google.com/groups?thre...606A%40msn.com


F W Green wrote:

I have added a button to a Toolbar to do a Bottom Double Border formatting
when clicked. However, it does not work and only puts a single border line.

If I have a Borders button in the Toolbar where I can select the Bottom
Double Border, it works.

If using the Borders button and I select DRAW BORDERS from the dropdown and
then select Bottom Double Border, the the Bottom Double Border button (which
did not work previously) works. But, when I close Excel or the file, this is
lost.

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Dave Peterson