Developers, repeat after me: invisible keyboards never work. Do you understand? Good. I hope we're clear on this. Because after trying to use the ridiculous "invisible" SnapKeys Si, which blocks more on-screen crap than any other input software I've ever seen, I'm ready to throw my beloved Nexus 7 through the next wall to look at me funny.
Here's the basic idea behind how SnapKeys Si works: Instead of being given a full QWERTY keyboard, you get a selection of twelve letters, divided among four colored blocks. If you want to type one of these letters, you just hit its block.