If you want to debug what’s happening after a pop up in SAP, you have to start the debugger (“/h” in the command field) before you go to the pop up screen. (Otherwise you will not be able to type “/h” in the command field with the popup screen) In that case you will have to execute unnecessary coding before you come in to the pop up.
To avoid this, you have an option of saving the “/h” (System command) as a shortcut in your machine. When the pop up is active, you can simply drag and drop that shortcut to the SAP screen to start your debug session.
Please feel free to post your suggestions, feedback and comments!