Microsoft apparently added transparent windows to Vista and 7. However, those windows only have transparent borders. To add greater transparency to windows, check out the Peek Through utility. With that software you can also click-through the transparent window to select options in background windows.
To add or install the Peek Through software to Windows XP, Vista and 7, the first thing that you need to do is to download it from this page. That saves it as a Zip file which you can extract by right-clicking it, selecting Extract All and choosing a path for the extracted folder. Then open the software’s window.
To add transparency to active windows, click the Transparency tab. You can drag the slider to the left or right adjust the transparency level. Click the Activate key on the Transparency tab, and then open a window. Press the Win + A hotkey to add transparency to the window as below.
You can also click-through transparent windows. Select the Options tab and the Allow click through of transparent windows check box. Open your browser and another window over it. Press the Win + A hotkey, and then you can select browser options and page links behind the active window as below.
So now you can select options in background windows without switching between them. As such, Peek Through is undoubtedly a handy addition to Windows.