I have a map on which I have used a fill rule.  I want to highlight the shapes on the map as I mouse over them.  The example does this by assigning one of a small set of styles to each polygon as it is loaded, but I can't use this technique because of the fill rule.

I can't find a simple method of getting the shape's colour and changing it when the mouse enters and back again when it leaves. What do I do to achieve simple highlighting?