Vista - Name of system color for IsMouseOver

When I move the mouse over a button it gets a yellow border.
I'd like to use this color to highlight a custom control of mine, but I
can't find the matching system color constant.

I thought it might be SystemColors.HotTrackBrushKey, but in my case
thats blue instead of the yellow I see in the button.

Can anybody tell me the name of this color? I already tried everyone
looking useful.

thanks,
Sam

Rather than trying to find the color use the binding feature to bind
the Color property (or any other property actually) of your custom
control to the property of the button.

Something like

<YourControl Color="{Binding ElementName=TheButton,
Path=BorderBrush}"></YourControl>