The author is frustrated with the lack of keyboard shortcut for switching between open windows on a Mac, specifically comparing it to the Windows and Linux equivalent. They discover an alternative solution called AltTab, an open-source app that provides a similar functionality to the Windows Alt+Tab feature, allowing users to switch between all open windows in multiple apps, with previews of each window. The author provides step-by-step instructions on how to use and customize AltTab to suit their needs.