[jQuery] jQuery 1.1.3+ jBlock-Pluggin

Seems that block pluggin doens't work the same way with jQuery 1.1.3
With 1.1.2:
- I had jBlock message with filter opacity in order to show a message
with "semi transparent" background.
With 1.1.3:
- Same code doesn't maintain the "opacity" and now is 100% (0
transparency).