The main window makes up the entire frame of the window, and holdsall of the windows smaller components. Therefore, it seems like a goodplace to start.
We’ll begin by creating a new document (Choose the document size based on how large you want your window to be). The background I’ll be using is shown below (You might be familiar with it from our Windows Vista Lighting Effect Tutorial).



We’re going to place the main window in the center of this new document. To create the box, select the Rounded Rectangle Tool from the toolbar, and then set the radius of the rectangle to 5px in the Options Bar. Select a foreground color of Black, and create a nice sized rectangle across your canvas.



Set the Blending Mode of this shape layer to “Lighten“. Doing this will keep the shape intact, and make blending options 100% visible, while making the black shape invisible.
Go into the Blending Options (Right Click Layer > Blending Options) and apply the following:




Phew… That’s a lot of styles…



It sure does come out looking nice though!