Alpha blend in grid selection not work in FireFox new version 13.0.1

[Youka]

Several days ago my FireFox browser was automatically updated to 13.0.1, now when I run the demo page of RAD Grid in this address, the selection function alpha effect is no more available but a blue block.

Address of demo:
http://demos.telerik.com/aspnet-ajax/grid/examples/generalfeatures/columntypes/defaultcs.aspx

Screen snapshot:
See attached JPG.

Related property: ClientSettings.EnableDragToSelectRows

Is this a conflict between RAD ajax control and FireFox 13.x new release?