Slimeblocks are added. Only 1.8. If you can't upgrade to 1.8, try tutorialz
Thats a idea to! Tip ; Use 1.8 and not hackclient. :)Or: To upgrade to 1.8, launch your launcher, click 'Edit Profile', under 'Use Version' change it to something about 1.8, then click Save Profile, launch like normal, and you're done!