SAMPLE: LBChange.exe Simulates Changing List Box Style

ID: Q84978

The information in this article applies to:

Microsoft Windows Software Development Kit (SDK) for Windows versions 3.0, 3.1

SUMMARY

The windows styles specified when an application creates a list box are fixed throughout its lifetime. LBChange.exe is a sample in the Microsoft Software Library that demonstrates how to use two list boxes to simulate changing the style of a list box.

MORE INFORMATION

The following file is available for download from the Microsoft Software Library:

 ~ LBChange.exe (size: 24180 bytes)

For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from
               Online Services

When it creates a new window, Windows stores window style information in several internal data structures. Windows refers to these data structures when it performs window management tasks, including painting the window.

If an application calls the SetWindowLong() function to change the window style dynamically, the new information is not reflected in the internal data structures. For example, an application can't effectively change a list box from the single selection style to the multiple selection style.

An application can work around this situation in two different ways:

Create two list boxes with different styles. The application shows the list box with the desired style and hides the other.
Destroy the existing list box and create a new list box in its place.

The LBCHANGE sample demonstrates the first method, which is simple to implement and runs efficiently. However, this method requires memory space to store two copies of the list box contents.

Although the second method uses memory more efficiently, it requires more work to implement. If the application changes the list box style often, managing the contents of the list box by saving and reloading the contents and tracking the selected items can become quite involved.

Additional query words: listbox Keywords : kbfile kbsample kb16bitonly kbCtrl kbListBox kbGrpUser kbWinOS310 kbWinOS300

Last Reviewed: December 26, 1998