SAMPLE: Code Implementing a Child Window with Menus

• Microsoft Windows Software Development Kit (SDK) for Windows version 3.1

SUMMARY

Child windows by design do not have menus; however, some applications may require such child windows. CHILDMNU demonstrates one way to embed a pop-up window with menus in a child window to simulate a child window with menus.

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MORE INFORMATION

Child windows were not designed to have menus but under certain circumstances an application may require a child window with menus. Below are the steps to simulate a child window with menus:

1. Create the child for a main window using standard methods.

2. Create a pop-up window without a caption or border. The pop-up window should take up the entire client area of the child window.

3. Moving: Set the child window as the parent of the pop-up window using SetParent(). This method clips the pop-up window to the child's client and moves the pop-up window relative to the child window when the child moves.

4. Sizing: If the child window has sizing borders, then the pop-up window must be adjusted as the child is sized.

   Correct sizing of the pop-up window can be accomplished by processing the child window's WM_SIZE message. When the child window receives a WM_SIZE message, the child's new client area is calculated and the pop-up window is adjusted.

5. Activation: Child windows are not activated by design. When the user clicks the pop-up window, activation is taken away from the main window and is given to the pop-up window. To simulate the main window's activation, the pop-up's window procedure, upon receiving a WM_ACTIVATE message, posts a WM_NCACTIVATE message to the main window.

   Note: This step causes flashing because the caption is repainted when going back and forth between the pop-up window and the main window. Unfortunately, there is no sure way to accomplish the change of caption's activation.

Other Considerations

Maximizing: When a child window is maximized, it uses the screen's maximum size. To have the child window act similar to an MDI child, two messages need to be processed; WM_SIZE in the main parent's window procedure and WM_GETMINMAXINFO in the child's window procedure.

WM_SIZE of the child's parent window procedure checks for SIZE_MAXIMIZE and SIZE_RESTORE. Then, if the child window is maximized, call ShowWindow() with SW_MAXIMIZED. This method adjusts the child window's size to the new size of the parent's client area.

On WM_GETMINMAXINFO of the child's window procedure, calculate the size of the parent's client area. Use the newly calculated size and set the ptMaxSize variable of the MINMAXINFO structure. This ensures that the child is always fully contained within its parent client area when maximized.