I've been using thunderbird lately and I like the unified inbox feature, where it aggregates messages in inboxes of your e-mail accounts in one place. This is also present in, for example, iOS 5.
But I prefer to use evolution, and from what I've seen, it doesn't have a proper Unified inbox but in previous versions it could be simulated with search folders (see http://www.svenbit.com/2011/05/create-a-unified-inbox-folder-in-evolution/).
In version 3.2 I could not find a way to create these search folders. Confusingly, the included help still talks about menu items that don't exist anymore (e.g. Edit → Search Folders doesn't exist, and Message → Create Rule just sends you to the filter setup dialog). And using Search → Advanced Search to search for both read and unread messages works, but only for the account I'm viewing at the moment, so it's useless.
I could set a filter up to flag all such emails from my inboxes as read and copy them to, say, the inbox in the "On this computer" pseudo-account, but it's obviously not the same, for example if I want to delete a message I just read, or if I was sent a big attachment that would get copied to my computer.
Is there any other way to achieve what I'm trying to do?