I've noticed some minor visual issues in Sample Browser when using the metro dark theme.
1. In chapter 10 - Intellisense Completion List the icons at the menu bar have the same color as in metro light which makes them hard to see. This also applies to any other chapter which has menu icons.
2. In same chapter when you open intellisense the tooltip for each entry has the same color as in metro light which means white background and black text. Same in insert snippet chapter and others.
3. In "Completion Filtering" chapter when you open the completion list in metro dark theme the menu at the bottom is unreadable since the forecolor of the text remains black.
4. If you start the sample browser and switch to Metro Dark immediately and then open the "Current Line Highlighting" chapter everything is okay so far. If you then switch to metro light the line highlighting color in the editor has changed although in menu it doesn't. Moreover if you try to change the color in the menu then nothing happens. You can check on / off the checkbox next to it but still nothing happens. When you switch a page back and then forward the line highlighting color is set to transparent. If you change it now it works.
5. Not an issue but I think a chapter demonstrating the multiple carets would be amazing since this is clearly an outstanding feature. It could let potential customers get aware of it and try it out.