How to change the outlining hover color in VS 2010?

If i hover over the thin vertical bar on the left, it highlights the entire scope of the block that's to the right. When t开发者_如何学Gohis scope is large, my entire screen flashes white (a consequence of my custom color scheme). Is there a way to change that color? i don't recall there being one when i made the theme.

It's Tools->Options->Environment->Fonts and Colors->Collapsible Region. The foreground color is the highlight on the margin, and the background color is the highlight in the text area.