What I Learned Building a macOS Window Manager Without Private APIs (opens in new tab)

I have been building a macOS window manager called SwipeX, and one thing became clear very quickly: moving windows on macOS is much harder than it looks. On the surface, window snapping sounds simple. Pick a target frame, move the window there, resize it, and you are done. In practice, macOS apps do not always behave that way. Some apps have strict minimum sizes. Some have custom title bars. Some expose extra accessibility windows. Finder may resize slowly. Xcode may refuse a requested width ...