From QB64 Wiki
The _WINDOWHASFOCUS function returns true (-1) if the current program's window has focus. Windows-only.
- hasFocus%% = _WINDOWHASFOCUS
- The function returns true (-1) if the current program is the topmost window on the user's desktop and has focus. If the current program is running behind another window, the function returns false (0).
- Not available in Linux or macOS.
- Build 20170924/68.
Example: Detecting if the current program has focus. Windows-only.
- Explanation: The program will display "*** Hi There! ***" while the window is the topmost and is being manipulated by the user. If another window, the taskbar or the desktop are clicked, the program window loses focus and the message "(ain't nobody looking...)" is displayed.