This lightweight plugin is based on the feature request from here. It forwards some useful mcMMO messages to the action chat. Instead that these messages spam the regular chat, you'll see them above the itembar and they will disappear after a shorten time. This plugin has no config. Just drop the plugin in your plugins folder and start your server.
You don't have to decompile the plugin. You can find there the source code with comments and building utilities.
mcMMOAction is open source and hosted on GitHub; feel free to fork, star, or contribute by making pull requests and opening issues.