The 2010.2 version of SyntaxEditor for WPF (and the same for the 2010.2 Silverlight Studio release) will get a new built-in language service called SquiggleTagQuickInfoProvider that you can register on your language. When this service is registered and the mouse is moved over a squiggle, it checks the squiggle data to see if there is related content available that can be displayed in an IntelliPrompt popup. If so, it displays it. Here’s and example of quick info for a parse error:
In this sample, we’re using the Web Languages Add-on’s XML language. The XML parser returned that there was a parse error because there is an unexpected duplicate end tag. We already have a built-in tagger that automatically looks for parse errors from a parser and makes squiggle lines in the editor for them. Now with this new quick info provider, mouse hovers over the squiggles will also show the text of the parse error.
If you have a parser on your language that is capable of returning parse errors, then it just takes two lines of code to register the parse error tagger (which renders the squiggles) and the new squiggle tag quick info provider, thereby giving you all this functionality.