Since Metro-style applications for Windows 8 should all have a touch-first experience, Microsoft has recently released a brief but useful “Windows 8 Touch Guidance” documentation on how developers should think about touch in their applications.
The four-page PDF touches (pun) on some interesting touch characteristics of Windows 8 – including but not limited to drag-down/up for select/deselect, semantic zoom and panning and swipe from edge.
The document also establishes some useful guidelines on content and interactive element placements for different grip positions – landscape and portrait, and positions – one hand, two hand, rested on surface or on stand. Through user research, Microsoft has also found a 7x7mm touch target optimal for the average index finger width of 11mm.
If you’re designing or developing a Metro-style app for Windows 8, make sure to add this document to your required reading list.