The tiles added can be configured from the main screen on the app with a new app bar button. (windowscentral.com)
We fixed an issue where the checkmark used to indicate a selected state in app bar toggle buttons wasn't visible in high contrast, for example in the Photos menu under ``...». (blogs.windows.com)
Windows 8.1 now uses context menus instead of app bars when you use a mouse. (howtogeek.com)