← v4 compatibility demos
Your Own Upload Button
Point InsertButtonID at any element you render yourself and it becomes
the browse button — the control's built-in button is hidden.
InsertButtonID stored to ViewState and was never read before 5.3.9,
so a v4 page with a styled browse button silently got the built-in one instead and
its own button did nothing. It now binds to the engine's browseButton.
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