So you want to open a task pane by using a button on the Ribbon. You also want a form region that appears in an e-mail item to detect the state of a control on a custom task pane so that you can add or remove an option that appears in a Ribbon menu right? Ok, I completely made this scenario up
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Do Your Outlook UI Elements Need Counseling? – Get your Form Regions, Ribbons, and Task Panes Talking to Each Other Again (Norm Estabrook)