I have recently noticed that the Aero shaders colorization is inaccurate compared to Windows 7, despite using the same exact color. I have pinpointed to this to version 2.3.0.2079-legacy and anything above it. You can see the differences between the colors here.
(OpenGlass v2.3.0.2079-legacy)
(OpenGlass v2.2.2.2046-legacy)
(Windows 7 glass)
You can see in these comparisons, it looks like it got brighter somehow.
I used the Architecture theme to compare these, I assume it might've happened during implementing the Windows Vista infrastructure. I hope this helps in some way however.