For those of you who have never changed the background color or didn't even know you could, here's how:
Go the the Application Menu (big red "A") and click the "Settings" button.
1. In the Options dialog box, click on the "Display" tab.
2. Click the "Colors..." button to display the "Drawing Window Colors" dialog.
3. Check that the Context is set to "2D model space" and then click "Uniform background" in the Interface element list.
4. Select a color.
5. Click the "Apply & Close" button.
You will now see the selected color displayed as the drawing area background. You might want to change the color of the grid to match.