Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

function GetSysFocus: Integer;
 var
   hFgWin, FgThreadID, hFocusWin: Integer;
 begin
   hFgWin     := GetForegroundWindow;
   FgThreadID := GetWindowThreadProcessID(hFgWin, nil);
   if AttachThreadInput(GetCurrentThreadID, FgThreadID, True) then
   begin
     hFocusWin := GetFocus;
     Result    := GetFocus;
     AttachThreadInput(GetCurrentThreadID, FgThreadID, False);
   end
   else
     Result := GetFocus;
 end;