Hi, I have created a Shared Add-in it contains a button, when you click on it, a System.Winidwos.Forms.Form shows up, now i have two problems that i can not solve them, 1. every time you click on the button it shows a new form, I want that it shows just one form not more, even if you clicked on button many times. I mean I don't want to disable the button , the button must be enabled always, because of the following point: 2. when you work on the office document the form lies in bakground, when you clik on the button the form must shows up agin . how? thanks you all