I browsed Liferea's site today and find out that they have released 1.4 stable version. I'm eager to try this out as i'm one of their users. I have successfully installed Liferea 1.2.x on my Slackware system and it's working very well and efficiently. Now, i'm trying to set up Liferea 1.4. Before you wanted to install liferea 1.4.x, make sure you have all your requirements installed first. Read my previous post about installing Liferea 1.2, since some packages is not available in Slackware's official packages, thus you need to install it manually.
One of the biggest change from liferea 1.2.x and 1.4.x is the storage engine. Liferea 1.4.x use Sqlite to store the feeds, so you will need to install sqlite first. Grab the Slackbuild and the source from Slackbuilds Repository and install it. Next, you can start compiling it or use the SlackBuilds (it's old, but you can edit the version and it might work. I don't use liferea's Slackbuild) instead. I use the first option by compiling from source. Everything works like before and here's the screenshot if you wonder what it's looks like: