The managed package framework for Visual Studio eats exceptions. I discovered this while building my own editor.

I started with the package that the wizard creates for you, but I needed different designer rather than the rich text box it gives you. I initially attempted to gut the designer and implement my own functionality. However, it kept throwing a strange exception on me that I could not correct.

I reverted back to the designer that was there, then created a DecisionTablePane class and implemented the interfaces that I thought I would need: IOleCommandTarget, IVsWindowPane, IVsTextLinesEvents. I left the NotImplementedExceptions in place thinking that I could then see what was being called. I changed the editor factory to instantiate the new editor. This worked, and I will refactor later to remove the classes I no longer need; I'm keeping them around to use as a guide.

I tried to open the file type I had registered with the editor, but nothing happened. I thought that maybe I missed an interface, but I couldn't find anything. I then stuck a breakpoint on the method I suspected was being called, and it got there. The exceptions were being consumed without any error reporting. This will make it difficult to debug my Visual Studio package. If something doesn't work, I may not even know it.