List of WPF functionalities that aren't in Silverlight 3

Question

A common technical decision nowadays is whether to build a ClickOnce rich client application or a web application.

Here I'm focussing primarily on choosing between a WPF application or a Silverlight application.

The chief benefit of Silverlight is obvious - it can be hosted in a browser.

But, if a programmer used to WPF was to start programing in Silverlight, what would he/she suddenly find is not possible or much harder?

Items can be of the following:

• You just cannot do it, period
• You can do it, but only sort of, with lots of caveats
• You can do it, but there's a lot more hoops to jump through

Examples I've stumbled on so far:

• Accessing the clipboard. You can only sort of do it, providing you're limited to Internet Explorer and you only write raw text
• Using Commands - Possible, but with a lot of extra work
• Context Menus - Possible but with a lot of extra work

What others?

Answer 1

Programmatic Differences Between Silverlight and WPF, A Whitepaper by Wintellect, LLC:

http://wpfslguidance.codeplex.com/Release/ProjectReleases.aspx?ReleaseId=28278

69 Pages, covers almost everything.

Answer 2

Cross-domain restrictions - Silverlight can only access sites which allow it via crossdomain.xml or clientaccesspolicy.xml.

For example, Silverlight can't communicate directly with Twitter's API or StackOverflow RSS feeds.