It's not just the drag and drop, it's the drag and drop and edit (single) callback. Like drag a button in the middle, resize it, change the text and then right-click and start coding what pushing it does. Now a days it's not push button but mouse over, mouse down, mouse up, press, long press, triggered, etc. etc. and I have to manually find or create the right source code file linking itself to the GUI form file.