Why do labels and frame have a "Tab Index" property in VB6?

Does anyone know why Labels and Frames (and possibly other开发者_高级运维 controls) have a TabIndex property in VB6? Is there some use for it; some feature of GUI programming I ought to be incorporating in my applications (that I am blissfully unaware of)?

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To confirm what Cody said in the comments. The VB6 manual entry for TabIndex says:

Controls that can't receive the focus (Frame and Label controls) remain in the tab order but are skipped during tabbing.

but

If you press the access key for a Frame or Label control, the focus moves to the next control in the tab order that can receive the focus.

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TabIndex is the property used to determine the sequence of focused controls when user presses TAB key.
If control with TabIndex=5 is focused and user presses TAB, control with TabIndex=6 will take focus.