Thread: Why UpdateWindow() after ShowWindow()?

In WinMain after you CreateWindow, there is:

Code:

ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);

I wasn't sure why UpdateWindow was there, so I temporarily took it out and the program did the same exact thing.

Can somebody explain this? I realize what UpdateWindow does (If there is an invalid region on the client area and UpdateWindow is called, then a WM_PAINT message bypasses the message queue and the WndProc proccesses the WM_PAINT message).

Thanks.

--Garfield

ShowWindow() only sets the "show-state". It doesn't actually force a painting so we do that by calling UpdateWindow() which forces the window to be painted.

exactly, so if you had to draw buttons or something on your window and you didn't have UpdateWindow() in there, you would have to force a repaint by dragging the window/minimizing it, etc. you could probably replace that with SendMessage(hwnd, WM_PAINT, 0, 0);