This tool main use is to prototype automation of different Windows programs with sequences of WinApi messages.
Apparently, for most of the programs, background input is supported, but it can get tricky.
For example, hotkeys like Ctrl+* work inconsistently on background.
Tool includes list of processes and windows handles (including non-top ones) and easy pick of visible windows under cursor. Messages preset (SendMessage, PostMessage, keybd_event) mimic standard key and mouse input and can easily be extended.
Made with Qt GUI, also uses threads just in case if they will be handy later. Based on my py-qt-extensions for PySide6 (QThread and QTimer and others).
Preview: