I've been asked to create a Custom Designer for Visual Studio. In this designer a programmer can create/edit Forms with controls and position them.
The input and result will be used and compiled by an external system (Sesam i've been told but never heard of it)
The format will be in XML.
The question is, where do I start, is it even feasible to create a Custom Designer?
You can create custom designers, but how you go about it depends on your requirements. If you're lucky, you can get away with a simple extension which handles editing certain types of files, such as the Snippet designer You can find the code for the extension on codeplex.
If you're not lucky, you may end up having to create your own project system. This is not an easy solution to implement, as it requires in-depth knowledge of VS.
Here's the documentation root for creating custom text editors, aka the simple route.
This is a good blog post from the XML team which details how they control what type of editor is used on XML files. Knowing how they accomplish this may help you determine if you can go for just a custom editor.
This thread on VSX (Visual Studio Extensibility) MSDN Forum will help you as well: Custom Forms Designer
来源：https://stackoverflow.com/questions/11101282/creating-a-custom-designer