Hi Zeeshan Ahmed Khan,
I suggest that you try the following:
1) Hook on the OnClientTabSelected event of the RadTabStrip.
2) Check whether this is the MultuPage that holds the RadListBox control
3) If so, find the listbox using $find and invoke its repaint() method. I suppose that this will have to be done with setTimeout. Example:
All the best,
the Telerik team