Many thanks for helps that I get, I'm able to store objects in Squeak.dll and use it with a exteranl program, main.exe.
Now I have Squeak.dll responding to main.exe. Say if I need a line, with startPoint, endPoint, colour etc.. I will ask Squeak.dll to create an object from Class Line, return the pointer to exe. While in exe, line is a struct that have sqPointer, startPoint, endPoint, etc.
Say if I have a function that ask Squeak to move the line. Squeak object(line) will then move, and instance variable endPoint will be change. There, Squeak should notify exe to update its value.
What should I do to achieve that? Simple variable pass in? or maybe call-back? Event notification?