Changing the window frame styles causes the window to disappear

This is a discussion on Changing the window frame styles causes the window to disappear within the Windows Programming forums, part of the Platform Specific Boards category; Ok so I have this function that will let you switch whether a window can be resized or not. Code: ...

  1. #1
    Registered User
    Join Date
    Aug 2005
    Posts
    96

    Changing the window frame styles causes the window to disappear

    Ok so I have this function that will let you switch whether a window can be resized or not.

    Code:
    void Window::SetResizable(bool resizable)
    {
        DWORD dwStyles;
        
        if (resizable)
            dwStyles = WS_OVERLAPPEDWINDOW;
        
        else
            dwStyles = WS_OVERLAPPEDWINDOW & ~WS_THICKFRAME & ~WS_MAXIMIZEBOX;
    
        SetWindowLongPtr(GetHandle(), GWL_STYLE, dwStyles);
        
        // When changing frame styles with SetWindowLong()/SetWindowLongPtr()
        // be sure to call SetWindowPos() with SWP_FRAMECHANGED
        // otherwise the non client area of the window won't be recalculated
        // until the window is sized.
        UINT uFlags = SWP_NOZORDER | SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED;
        
        SetWindowPos(GetHandle(), // the window handle
                     HWND_TOP,    // the window to insert after
                     0,           // x
                     0,           // y
                     0,           // width
                     0,           // height
                     uFlags);     // flags
    }
    Now this works great, with one minor flaw.
    If the window was visible *before* I call this function,
    the window disappears off the screen leaving behind artifacts on the screen.

    I hacked up a fix, but I want to know why this happens.

    Here is the fix:
    Code:
    bool wasVisible = IsVisible();
    
    all that other code
    ....
    
    if (wasVisible)
       Show();
    Last edited by sethjackson; 08-12-2010 at 04:44 PM.

  2. #2
    'Allo, 'Allo, Allo
    Join Date
    Apr 2008
    Posts
    611
    Quote Originally Posted by sethjackson View Post
    I hacked up a fix, but I want to know why this happens.
    The WS_VISIBLE bit isn't set in the new mask.

  3. #3
    Registered User
    Join Date
    Aug 2005
    Posts
    96
    Quote Originally Posted by adeyblue View Post
    The WS_VISIBLE bit isn't set in the new mask.
    LOL I'm an idiot. Thanks.

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