So find out why a certain error situation was triggered, it can be a good idea to set a break point somewhere above this point and then follow the execution of the program to see what is happening. A break point is a point in your code where the execution will stop and hands over control to the developer. Using F7 or F8 (or the mouse with the icons, see the main page) you can step into the next code line. 


To use the breakpoints you must apply them in your generated code. After all, this is the code that is actually running. Locate the line where you want the execution to pause and click with the mouse on the beginning of the line in the line-number area.



To locate the spot where your own code is inserted follow the next rules:


The event code is generated in the component that applies. It is generated at the end of the module:



In this case the onClick code is added to the code that is generated for btn_1:



To reset this break point, click again in the line number area on the correct line. 


When will the break point trigger?

The logical answer is: when the code reaches that point. So in this case after you click the button. But as the IDE will break on each entry of the controller application, you have to continue execution until all data is on your form. As that can be inconvenient you can use the fast mode button.