A method and system for rendering a desktop on a computer using a composited desktop model operating system are disclosed. A composited desktop window manager, upon receiving content information from application programs, draws the window to a buffer memory for future reference, and takes advantage of advanced graphics hardware and visual effects to render windows based on content on which they are drawn. The windows may also be rendered based on environment variables including virtual light sources. The frame portion of each window may be generated by pixel shading a bitmap having the appearance of frosted glass based on the content of the desktop on top of which the frame is displayed. Legacy support is provided so that the operating system can draw and render windows generated by legacy applications to look consistent with non-legacy application windows.