LyteByte

Windows Vista Aero has cool features of transparency which are not available in Windows Vista Basic. But these transparencies are not available when the windows are maximized. The corners and the top portion of the windows are transparent when they don’t occupy the whole screen but when they are maximized to full screen; these transparent areas are replaced with black color or with base color of your choice in the windows personalization.

So when you set the transparency to maximum even when all the windows maximized, you don’t have the non-transparent regions anymore but rather the dull background of what’s beneath. These features can be not only seen on the top of the windows but also the taskbar. Also, in applications like Windows Media Player where you get the transparency in the control panel region, at the bottom of the player even when it’s maximized.

Here are some pictures for you to understand what I am referring.

Windows Not Transparent when Maximized

Click here to see the full screen view

Windows Transparent when maximized

Click here to view to the full screen view

So how to get full transparency in Vista when the windows are maximized?

Note: These tweaks require registry changes. If you are not comfortable with registry changes, do take a backup of registry files and I am not responsible of other consequences of the change.

With few changes in uxtheme.dll, themeui.dll and shsvcs.dll you will be able to get the desired effect but there is a setup provided by VistaGlazz which does the same thing which can help you to patch the files safely and unpatch it if necessary.
VistaGlazz helps not only to keep the maximized windows transparent but also unlock Windows desktop Manager so that it allows adding custom Visual Styles.

Download VistaGlazz from Download.com or VistaGlazz

Steps to follow:

After downloading, Run the setup file (VistaGlazz.exe) to patch the settings.

Click the system Icon and click patch originals to patch the system files. You will need to reboot the system for the changes to effect.

Run VistaGlazz.exe again and click the Style file and click patch style. This doesn’t require restarting the system. The theme service will automatically restart and apply the new theme.

Now you will have the transparent feature of Vista Aero even when the windows are maximized.