Software Planner newsletter
If your looking for an overview of test cases for testing the user interface you could start with the Software Planner newsletters from Steve Miller. For the last two news letters he has focused on this area. In August it was "20 Useful test cases for testing User Interfaces" and this month it is "15 Useful test cases for ensuring a consistent User Interface".
Examples of the test cases include:
Screen font type: Ensure that the screen font family matches from screen to screen. Mismatching fonts within the same sentence and overuse of different fonts can detract from the professionalism of your software user interface.
Screen font sizes: Ensure that the screen font sizes match from screen to screen. A good user interface will have an accompanying style guide that explicitly defines the font type and size for headers, body text, footers, etc.
Error logging: If fatal errors occur as users use your application, ensure that your applications writes those errors to a log file, event viewer or a database table for later review. Log the routine the error was in, the person logged on, and the date/time of the error.
Error messages: Ensure that error messages are informative, grammatically correct, and not condescending.