As I promised in the post about my Firefox Debug Helper Visual Studio Add-in, I present you the top three pitfalls I stumbled across when I was trying to develop that add-in. Some of the problems I came across (and their solutions) really weren't obvious, so I hope this post will help others in some way. The topics I'm going to cover are:

1. Problems when capturing Visual Studio events
2. Debugger events/operations being non-reentrant
3. Features "hidden" in interface implementations

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Ever since the release of Firefox 3.6.4 (and its new plug-in isolation feature), a smooth debugging experience for Silverlight developers who use that browser went away. The problem is that Visual Studio attaches correctly to the Firefox process; however, all Silverlight applications now run in a separate process called 'plugin-container.exe', and so the debugger is not able to find them. You're now left with three options:

1. Either attach to the correct process manually each time you want to debug a Silverlight application or
2. Disable the feature altogether or
3. Switch to a different browser

Option 1 is pretty tedious work if you have to do it over and over again, all day long. Option 2 on the other hand is a dangerous thing to do, because disabling that feature is not straight forward, which means that you're now testing your application in a different environment than 99,9% of all your users. Unfortunately, Silverlight behaves differently with or without that option enabled in some scenarios, so turning that feature off is not recommended - unless you want to risk that serious bugs slip through undiscovered and in the worst case surface only at your users. Finally, Option 3 was not an option for me out of personal taste. More...

When Firefox 3.6.4 introduced a new plug-in isolation feature (basically they are running plug-in content like Silverlight or Flash now in a separate process), one of my business applications suddenly stopped working. That is, it returned random errors when I was communicating to a server, and often the Silverlight plug-in in Firefox crashed. In Firefox 3.6.3 and all other browsers I tested, everything was fine. It took me a while to find the reason for this, and then I posted a bug report to Bugzilla, Firefox's issue tracking system. Later, I was contacted by someone from Microsoft and sent in a demo project too. When Tim Heuer was discussing the upcoming service release for Silverlight, he also mentioned bug fixes specific to Firefox, so my hopes were high that these issues would be fixed, but now that the service release is here, I see they're not. Again I was asked by someone else at Microsoft to send in a demo project, and that when I thought of also writing this post :). You can download the complete project at the end of the post. More...