@Sven Groot: The "include a search bar / icon if search is integral to your app" recommendation is actually a very recent change to the guidelines (added between RP and RTM - so no, the Wikipedia app devs couldn't have studied it a little better), prior to that the advice on in-app search UI was a straight "don't do it". (Another change is that the "type to search" behavior seen on the Start screen and now the Store is now recommended for all applicable apps, and built in to the frameworks. I would guess we'll see it added to most of the other built-in apps at or soon after GA.)

I think the main reason the Windows team generally discourages apps from including search boxes though is because they're afraid users won't learn to use the Search charm otherwise - i.e. if some apps start including search boxes, that will become the standard method of searching and all apps will "have to" include them, meaning a little more clutter for everyone. OTOH if all apps "hold the line" and rely on the Search charm instead, everyone will get accustomed to the Search charm method and every app's canvas / app bar gets a little more space and a little less clutter, plus a little more consistency. That's the idea anyway. Smiley I personally think it would've been awesome if the Bing app shipped showing just the background with no visible UI at all, and relied on type-to-search, but guess it wasn't to be Sad

For me the horizontal/vertical mousewheel thing felt weird for about fifteen seconds and now I'm not consciously aware of it at all, I just scroll. shrug