I came to say the same. ResEdit was true tinkering... you could swap images, change user visible strings, menu items... I even managed to remove copy protection

I came to say the same. ResEdit was true tinkering... you could swap images, change user visible strings, menu items... I even managed to remove copy protection from a game (which I didn't have any way of purchasing due to being in a different country and stuff) which was compiled with (some) symbols and even though I didn't know 68000 assembly I figured out how to skip the call to the function which asked you for some word in the game's manual. Years later, programming in Win32, I found you could do a lot of tinkering by getting window handles to windows and UI elements of other programs and changing attributes / calling various functions. I don't think this was exploited nearly enough by the curious youth. These days if you show a kid that if you type javascript:document.body.contentEditable=true in the address bar you can change the contents of a web page just by clicking and typing they'll have a great time creating fake news items, etc.