Delphi/Lazarus: Get Handle of Window under Mouse Cursor

First of all, you have to determine the current mouse position. This can be done using the function GetCursorPos(). After that, you can use the function WindowFromPoint() to specify the window at this position.

Here is an example:

var
  ACursorPos: TPoint;
  AHandle: HWND;
begin

  if GetCursorPos(ACursorPos) then begin

     AHandle := WindowFromPoint(ACursorPos);

     if AHandle <> 0 then begin
        SendMessage(AHandle, ..., ..., ...);
     end;
  end;  

end;

Because both functions may fail, you should implement conditions like I have done in the example. Only if you are sure that the Handle is not 0, that means, a window was found, you should go on and use the Handle. In the example above, we are sending a message to the corresponding window.
Last update on 2023-03-22 | Created on 2015-12-24