MessageBox Problem

Hello everybody. I''am developing a 3d-world editor in Win32. The main window creates a OpenGL context that is used to render the scene. The problem is when I try to display a message box using the API MessageBox function. The main window lost the focus, but the dialog isn´t shown. I have tried all styles for the dialog box but no one doesn''t work. The only strange thing I make with the main Window is make it to be the foreground window with the SetForegroundWindow function and then set the focus to it with the SetFocus function. The styles I are using for the window class are : - CS_HREDRAW, CS_VREDRAW and CS_OWNDC The styles I pass to CreateWindow function are : - WS_MINIMIZEBOX, WS_VISIBLE, WS_CLIPSIBLINGS, WS_CLIPCHILDREN, WS_MAXIMIZEBOX, WS_CAPTION, WS_BORDER, WS_SYSMENU and WS_THICKFRAME. Someone has any idea to solve that problem? Thanx to all !!!