One of my favorite Colorado community leaders and XAML Jedi, Shawn Kendrot, wrote a great article helping XAML developers dynamically style controls with the standard light and dark layouts. In his article, Shawn uses the Settings charm to show how to do it.
One of the things I love about Windows Store apps is their ability to integrate with the system. One of these integration points is the Settings Charm. I’m not going to show you how to create a settings flyout. There are already lots of examples out there that do this. There are even some helpers like the SettingsFlyout available in Callisto and the helper created by Jerry Nixon. Recently Tim Heuer made a change to the SettingsFlyout to set the background to white. This change allows your app to follow the guidelines. He also added a property that allows you to change what you want the background to be if you are not a fan of white.
This change to the background works great if your app has a light requested theme. If you are using the default dark theme then the new background on the flyout becomes a nightmare. It’s a nightmare because now you have to style all of the controls you use for your settings to work properly with a light theme. You could easily start changing the brushes of various properties, but this doesn’t look very polished. You could restyle the controls and start to guess and what colors to use for this or that, but you’ll forget something (at least I did, and it was a lot).
There has to be an easy way to get light themed styles at runtime, right? I couldn’t find one, but I did find a way to easily create them. The resources and styles used by controls within the app are generally not found within the app itself. The app requests a theme from the system and that theme has all of resources and styles. This allows you to create custom controls and use those brushes and have the control be styled properly for both light and dark themed apps. These resources are not found within your app, but they are on your machine.
The styles and resources for WinRT are found at C:\Program Files (x86)\Windows Kits\8.0\Include\WinRT\Xaml\Design. This folder has two files in it. The themeresource.xaml file has all of the brushes, and other resources like font size and opacity. The generic.xaml file has all of these resources as well as all of the styles for each control. We can use these files to build our light themed styles.
Read the whole article here