In the ribbon, I want to insert a picture or a link into a content page, but the "From Sharepoint" button is grayed out and I can only upload an image or insert a link "From Address". My field is rich text. I'm using SharePoint 2010.
How can I make the link available? Thanks
Usually ribbon button is grayed out if you didn't add CommandUIHandler element for it in your CustomAction XML.
For more details, you can see this MSDN article:
http://msdn.microsoft.com/en-us/library/ff458385.aspx
Also, you can find useful this article (with sample code and screenshot):
http://blogs.msdn.com/b/jfrost/archive/2009/11/06/adding-custom-button-to-the-sharepoint-2010-ribbon.aspx