Set text in edit control on inspector window indicating time Outlook 2007

[saniltalathi]

Hi All,
I am developing COM Add In for outlook 2007. On Inspector window i have added one edit box(using Ribbon XML), in that edit box i have to show timer indicating how much time is spent while reading or composing mail. My Problem is how should i set timer on the inspector window so each inspector window has different time depending on when they are created. I have callback function which will take text of the edit control, also i am invalidating that control so when time changes my callback function will be called to set the text.
Any help or suggestion will be appreciated.