I once took a contract to build a tool in Excel that I thought was relatively straightforward -- but they needed it on a version of Excel that was right before

I once took a contract to build a tool in Excel that I thought was relatively straightforward -- but they needed it on a version of Excel that was right before VBA was supported. So I tried to re-work the app using Windows event macros. It was a mess. This was like you just re-play a stream of user input events into the Windows GUI: "click the mouse at position 200,120" in order to hit the appropriate button on an Excel dialog box. What an idiot I was... But before Excel had an API, that's all there was. "Steps Recorder". Ugh.