procedure TForm1.Button1Click(Sender: TObject);
begin
if Tag=0 then
begin
SetWindowPos(Handle, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE or SWP_NOSIZE or SWP_NOACTIVATE);
Tag := 1;
end
else
begin
SetWindowPos(Handle, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOMOVE or SWP_NOSIZE or SWP_NOACTIVATE);
Tag := 0;
end;
end;