The mouse is hovering above the button on the right, showing the transparency effect. It's the same for the other button. The power button (top right) also displays on-hover transparency effects.
I've included Replacer (with permission) to help with replacing the original logonui.exe. However, I'd strongly recommend the LogonUIBoot Randomizer
which makes using several LogonUI screens very easy.
I've included three other versions of this (in my scraps): Blue
The photo was taken by me. Any comments and criticism are greatly appreciated.