class GuiWaitTest
{

protected:
	DWORD old;
	DWORD now;
	unsigned int delay;
	void init()
	{
		now = ::GetTickCount();
		old = now - delay;
	}

public:
	GuiWaitTest(void) : delay(100)
	{
		init();
	}

	GuiWaitTest( unsigned int delay ) : delay( 100 )
	{
		init();
	}
	
	GuiWaitTest& operator=( const unsigned int delay )
	{
		this->delay = delay;
		return *this;
	}

	bool operator()()
	{
		now = GetTickCount();
		bool result = ::abs(static_cast<long>( now - old ) ) >= static_cast<long>(delay);
		if ( result )
		{
			old = now;
		}
		return result;
	}

	~GuiWaitTest(void)
	{
	}
};

for ( MyVar var = SomeOperation(); var.GetData().IsNotNull(); var = SomeOperation() )
{
  // Here, 'check_gui' is a member variable of type GuiWaitTest.
  // my_control is a read-only control in the GUI that only displays state.
  // as such, my_control is only displaying progress... it has no other purpose.
  if ( this->check_gui() )
  {
     my_control.SetData( var.GetData() );
     my_control.ProcessEvents();
  }
}