Problems with refreshing a draggable MFC window

Greetings.

I have to make a draggable MFC dialog window, which has a background - used that: http://www.codeproject.com/KB/graphics/picturewindow.aspx - and has several picturebox controls. I have tried two approaches, and while they do work, they have some problems.

First approach is "Manual" - on the 开发者_JAVA百科LBUTTONDOWN message I check if it;s on a clean area of my window, and set a flag variable. On MOUSEMOVE, the flag is checked and if it's set, a MoveWindow function is called, and then, Invalidate(1). On LBUTTONUP, flag is unset. This approach works correctly and redraws as needed, but is somehow very slow - if I'm moving the cursor too fast, the window falls behing and isn't dragged, as cursor's not over the window anymore.

The second approach is "Automatic" - I just call

DefWindowProc(WM_SYSCOMMAND, SC_MOVE+2,MAKELPARAM(point.x,point.y));

on LBUTTONDOWN, and it handles the rest, it's quick and never fall behind, but when I drag it over screen's edge ( so that some part of the window gets invisible), when I drag it back, all the controls get invisible and are not refreshed, background is okay. I suppose that's because Invalidate() isn't called during movement that way, as I actually call it after calling DefWindowProc() and so, everything is refreshed properly when I depress the button.

What should I do to improve either of those solutions? I need it both fast and correct. I may have not provided some required information, I'll add it is need arise.

Thanks in advance.

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Solved the problem, by modifying the second way. I added a total redraw to the OnPaint(), and to get rid of flicker, I only redraw durng dragging, by using a flag variable.