I've looked at the Office Dev Center and Napa documentation, but this is still unclear to me. This link:
http://dev.office.com/docs/add-ins/overview/office-add-ins
Has a "Word, Excel, and PowerPoint Add-ins that extend functionality" section with task bars and a "Excel and PowerPoint add-ins that create new objects" section, implying that task bars do not create new objects; is this the case?