Event when displaying scrollbar

Hi all!
I have a scrollpane where the items shown is "tabbed" up from left to rigth in the pane. It is name (a tab) number (a tab) date ant that covers the entire scrollpane (this to make som space between the different colums).
Now when it is to many items in the list to show, a vertical scrollbar is added, I have set

My problem is that when the scrollbar is displayed, all my text dont fit in the scrollpane. What I need to do is to change the tabs when the scrollbar is added or removed. My question is if there are some event that will trigger when the scrollbar is added or deleted? If not, is there some other way to solve this?
Thanks in advance,
Andreas