I added a custom group to the TabNewMailMessage Tab in the Outlook
2007 Ribbon. The xml for the custom group is below.

customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui"
onLoad="Ribbon_OnLoad"
ribbon
tabs
tab idMso="TabNewMailMessage"
group id="EncryptionGroup"
getVisible="EncryptionGroup_GetVisible"
getLabel="EncryptionGroup_GetLabel"
toggleButton
id="EncryptButton"
getLabel = "EncryptButton_GetLabel"
getSupertip="EncryptButton_GetSupertip"
onAction ="EncryptButton_Action"
imageMso="Lock"
/
toggleButton
id="DoNotEncryptButton"
getLabel = "DoNotEncryptButton_GetLabel"
getSupertip="DoNotEncryptButton_GetSupertip"
onAction ="DoNotEncryptButton_Action"
imageMso="ReadingViewShowPrintedPage"
/
/group
/tab
/tabs
/ribbon
/customUI

As you can see I have two toggle buttons in my group. I want to be
able to make them toggle mutually exclusive. When the onAction event
fires on one I would like to be able to set the state on the other
button to up. I can't figure out from the parameters of the method
(Office.IRibbonControl control, bool isPressed) how to get access to
the other button. I am new to Outlook extensions so this is probably
something simple I just haven't seen it.

Let me know if you have any questions.