I can search for communities in the little list box at the bottom. I have absolutely no idea how to search for posts or comments (other than using DuckDuckGo or whatever).
Can you search for new community also? Because it seems for me it is only to search for subscribed community only?
Oh, there it is... I had tried using that before but it was only showing the communities I had already subscribed to. Now that I've tried it again its showing other communities too. I'm assuming the server just must have been overloaded when I tried it.