Determining Toolwindow content ActualWidth in Windows 8

Hi, I have built a dashboard analysis application using Actipro - I currently have a main toolwindow containing many toolwindows (each a different wpf chart). The user can add new child toolwindows and move the toolwindows around inside the main toolwindow (all set to inner-fill). Every toolwindow contains a docksite which nests other toolwindows/docksites.

Everything works fine in XP/Vista/Windows 7. However the following issue is occuring in Windows 8.....

I need to determine the Width of the toolwindow (or actually the toolwindow content) for display purposes within my application. In Windows XP/Vista/7 the correct width is obtained when either displaying the Toolwindow ActualWidth; the Toolwindow Content ActualWidth; or the DockSite ActualWidth which is contained inside the toolwindow. In these operating systems all the values are the same and correct. But in Windows 8 the values I am getting for all 3 is way off the mark (i.e. I am getting a value of 1327 instead of the expected value of 1920 for all 3). Do you have any ideas what could be causing this or if this is a known issue with Windows 8.

Thanks