Might be my old eyes, or attn span.
It to easy to miss that a topic is locked.
I visited a locked thread.
didn't even notice the lock symbol on the main page.
even harder to see the "lock" inside the thread.
wasn't till I started wondering where did the reply button disappear too, that i caught on it's locked.
23px × 16px, + image coloring, + not very contrasting background color, + it's me, ... just wasn't very noticable.
We could improve the fast that a topic is locked in the topic listing
Maybe use the "locked" text in front of the topic subject in the listing (like what we do for a topic that is awaiting approval.
Or add a subtle cross hatch to the line in the topic listing.
Or change the message icon to a lock in the listing
Going to the topic itself, maybe it should indicate its locked in the top header, or instead of the hidden reply button, use the locked icon?
Like this maybe
Force the locked message icon
(Link-4363) Or prefix with text
(Link-4365)