Guidance for building and debugging Godot 4 transparent desktop-widget games — "passthrough games" such as desktop pets, idle widgets, and screen-edge companions whose window is transparent and lets clicks fall through to the desktop where there is no game content. Use this whenever working on a Godot project that has a transparent, borderless, or always-on-top window, is a desktop pet / widget / overlay, or implements mouse click-through / passthrough — and especially when debugging its signature failure modes: clicks not registering, the whole window swallowing or passing every click through (often Windows-only), or a transparent window rendering as a solid black rectan…
