That's fine... just so you know for future, you could have still use the combobox - by binding the Item selected label in behavior tab to the destination of Pie chart mouse-over cell - then user dont have to select the country from the selector. The combobox will automatically filter on the country as it changes. Then you send the combobox behind some background so that user don't see it.
Here is a nice article about the same approach that could fit your scenario (unless I am missing something)
http://infosolblog.com/customizing-selection-de-selection-in-dashboard-data-hierarchies/
Thanks for sharing!
Runali