This is the time it takes for the blur to "fade in", in milliseconds.
The colors to use for the overlay on all GUI backgrounds. The value here is a hexadecimal color value, in the format ARGB (alpha first, then rgb). Because the background is a gradient, two colors can be specified. The default is black with a 45% alpha value (75000000).
A list of classes to be excluded from the blur shader. This is to be used for GUIs which do not necessarily cover the screen. It defaults to containing only one GUI, the chat.