Collection widget: Deleted cell's height remains...

Hello all,

I have a collection widget with in each cell a button 'delete' to delete that particular cell.

When I click on this button, it call the service 'GetMashupsToDisplay' and deletes the according row in its infotable.

So the result = all cells minus the row for the deleted cell. (= OK)

Now on my dashboard, the cell is deleted as well. (= OK) However, it seems the height of the 'deleted' cell remains present and now there is a white hole between my cells... (= not ok!)

How does this happen?? How to solve this??