I'm not familiar with these. Are the properties and methods that dynamically add visible in the code editor?

It seems C# work by subclassing the DynamicObject class. What about dynamically extending all the other existing C# classes?

What if I subclassed a C# Queue as MyQueue and then while my days long simulation was running I wanted add an instance variable 'trackCount' to all existing MyQueue instances? In Pharo all you do is this...

Queue subclass: #MyQueue instanceVariableNames: ’trackCount’ classVariableNames: ’’ poolDictionaries: ’’ category: ’Example’

and program keeps running, this definition is updated in the editor.