ILSpy icon bar
In ILSpy 2.0, a new UI element has appeared: icon bar margin
The margin contains all icons for C# types and members. When you open ILSpy, the icon bar is on the left hand side of the text editor and it looks like this:
The users can interact with the icon bar (through mouse left/right click). When right clicking on an icon, a context menu appears and you can analyze the type or member.
From the programming point of view, one can use MEF to extend the functionalities (one example is the ILSpy breakpoints).