Tinkle is a macOS app which appends visual effect for focused window changes.
It helps finding the focused window when you switched it by keyboard shortcuts.
macOS Catalina (10.15) or later.
Tinkle requires accessibility features in order to detect the focused window changes.
Using a pre-built binary
Building from source code
Execute make command on the terminal.
make -C src
src/build/Release/Tinkle.app is a built file.