Dashboard "Updates to your tickets" mark checked

Dear sir,

I would like to propose a small improvement to the dashboard, in "Updates to your tickets" section. I find this information very useful, but while clicking on different tickets, I don't remember which I already checked and which not. It would be very nice to have some sign (maybe color change) which would tell me if I already clicked that update. In that case all updates reffering to the same ticket should change color.

Thanks in advance!
Benjamin