Some people may not know this. So I suggested adding it in here.
When you are debugging, you see the call stack, usually at the bottom of the screen. You can double click on second or third line and debug window will point to the code on where it was called from so you can see all the from the begging of the call stack and how it got there.
This makes it easy to find out why the function or CU was called.
So the trick is to double click on other lines in the call stack to see the code.
Ahmed Rashed Amini