Over the last couple of years, the iPhone has greatly popularized the tab bar navigational model for mobile handsets. Apple has put together a design rationale for the tab bar in their Human Interface Guidelines (HIG) along with lots and lots of other information — they do however leave some question unanswered. Having worked with interaction and graphical design for iPhone applications during the last couple of years I’ve managed to pick up some lessons the hard way, and in this post I would like to share my thoughts on a couple of do’s and don’ts. So says Petter Silfver within his blog on Significant Pixels where he compares different…