Moving the Text drawn by TextOut() Function

I'm trying to redraw some text I drew on window at x and y coordinates say (100, 100) to a new location (500, 500). when I redraw the text, it doesn't erase the old text at (100, 100)开发者_StackOverflow社区 until I refresh the window (like do a minimize and maximum). how can you update the window to display the current text?

InvalidateRect, UpdateWindow.