Responsive Popup for Notifications

Hello,

I would like to make a Popup for displaying the latest 5 notifications in my project and the popup should appear on clicking a bell Icon. I have used collections to achieve the same as of now with a mashup as modal popup. But the size of the popup should be made responsive that is based on the number of notifications (No scroll bar should be present). Currently I am doing it by bind the "PopUpHeight" property of the Navigation Function. But I would like to add a button in the bottom of the Popup which links to another mashup. But When I am adding a row to put a button , the Popup size breaks that is the bottom row size increases and decreases unnecessarily. The Row size is not a bindable property. I want the Bottom row size to remain constant and Top row to change dynamically or any other approaches are welcome. I am Using ThingWorx 8.5.

I am posting a picture of what I view i would like to have.

Kindly provide any workaround 

Thank You