Readonly DoubleEditBox issues

I have some controls defined like this:

<editors:DoubleEditBox HorizontalAlignment="Left"
                       CenterSlotHorizontalAlignment="Right"
                       IsReadOnly="True"
                       IsTabStop="False" />

So, these are read-only, and I don't want the user to be able to tab to them. But setting IsTabStop to false seems to have no effect. Also, if I set the background to something like light gray, when I set the focus in the control, the background reverts to white. Although I don't want the user to tab to the controls, I don't mind if he sets the focus with the mouse (maybe to copy the value), in that case I don't want to lose my "read-only" color.

So I guess that's two questions  :)