Step 1: Create an Interface Window
Step 2: Put the output object on the window
Step 3: Make the output objects background a color you would not use in the window, and make the font's color different from that
Step 4: Go to the window's settings, and check "Set Transparent Color To Image" and choose the output objects background color.
Make sure you use a separate window for it than the others, or you'd be able to see things like your web browser through your interface. :/