Every app or mobile game must have what's known as a layered interface. There also should be thumb-focused interactions, simple typefaces and all kinds of swiping. At least, those are some of the user experience design trends that seem to be prevalent today. Developers may need to upgrade their skill set to know what will be hot in mobile UX tomorrow. Both Google (NASDAQ: GOOG) and Apple (NASDAQ: AAPL) have been taking steps to make sure their developers keep up with changes and trends in UX design. The push from platform providers comes as little surprise to developers and other experts in UX design, who suggest that the companies want to ensure that all the products flooding their app stores achieve a more consistent level of quality. For more on this trend, check out this FierceDeveloper special report.