This variable is designed for thin client applications. It provides some control over when the runtime generates Msg-Tv-Selchanging events for tree view controls. Because most applications that use tree view controls do not process Msg-Tv-Selchanging events, the thin client suppresses its generation in some cases. This improves both performance and stability. TC_TV_SELCHANGING recognizes the following values:

0 never generate Msg-Tv-Selchanging events
1 (default) generate Msg-Tv-Selchanging events when the selection is about to change due to the user using the mouse or the keyboard to change to current selection
2 always generate Msg-Tv-Selchanging events

The default setting of 1 allows you to detect user-initiated events in your program while filtering out many other causes of the event.

If you know your program doesn't handle any Msg-Tv-Selchanging events, you can set TC_TV_SELCHANGING to 0 to entirely inhibit generation of the event. This can slightly improve performance.

If TC_TV_SELCHANGING is set to 1 and your program experiences odd behavior with tree view controls under the thin client, you can try setting the variable to 2 to generate all Msg-Tv-Selchanging events. This setting can help you determine whether a Msg-Tv-Selchanging event is the cause of the odd behavior. If this setting eliminates the odd behavior, it indicates that your program relies on Msg-Tv-Selchanging events in cases other than the user initiating a selection change.

For more information about the thin client, refer to the AcuConnect User's Guide.