How to fire the change event of property panel texbox

i would like to know is there any way to fire the change event of the property panel textbox manually.

i have a custom filed on the property panel. and i want to update the text of the textbox from a popup selection.

i am doing the set and get method to update the business object and retrieve it.But the problem is its not updating in the view. because the change event is not firing.

Thanks.