Instead of presenting guest users with no permission to post a button that says "You cannot start a new topic" (or similar when trying to reply), why not change this to a button that tries to get members to sign up?

I've changed this manually in my templates so that instead of this button, guests see something that asks them to sign up to reply (with link). This has increased guest signup rates by around 30% overnight. Really simple change and it's very effective! I'm sure this would be welcome in the core package.

This is a clever idea! Thanks for sharing.

Great idea! I'd like this as well. :)

Great idea!
Any tips on how you specifically did it?

Figured it out:

In your template, edit topicViewTemplate
Find this line:

<li class='disabled'><span>{$this->lang->words['top_cannot_reply']}</span></li>

Replace with

<li class='disabled'><span><a href="http://www.YOURWEBSITE.com/forum/index.php?app=core&module=global&section=register">{$this->lang->words['top_cannot_reply']}</a></span></li>

Then edit forumIndexTemplate and find both instances of

<li class='disabled'><span>{$this->lang->words['forum_no_start_topic']}</span></li>

and replace with

<li class='disabled'><span><a href="http://www.YOURWEBSITE.com/forum/index.php?app=core&module=global&section=register">{$this->lang->words['forum_no_start_topic']}</a></span></li>

Then edit your language pack and change forum_no_start_topic and top_cannot_reply to whatever you want (eg "Register to start a new topic").

I'm sure someone else could do it neater than me (I suspect I shouldn't need the full URL there) but this works.

Thanks. How do you change the color of that button?

Hi it all worked fine but I dont understand the language pack bit. Please explain how to do this?