Expand Syntax to Fill Area

I’m using a Static widget to display a Rich Syntax highlighted code view, but I’d like it to expand to fill the view. The static widget itself is set to fill the height, but the Syntax renderable only fills as much as the source itself fills vertically. Is there a way to force the syntax renderable to render lines to fill the Static widget, or at least a sane way to find the background color used by a specific syntax theme in order to make the background of the static widget match the background of the code?