Lack of background-color in gradients.

For some cases like IE9 (non-compat mode) where you can only have one filter applied at a time or any time a gradient filter is set as disabled (enabled=false) the background color is non-existent or gray.
There should be a valid approximation/fallback for these cases.
Regardless if it only happens in IE9, if the style is overridden and the filter is specified to be disabled, there will not be a background color.  There should be.