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Occurs when the user displays or closes the custom task pane, or when code changes the value of the Visible property.
Assembly: Microsoft.Office.Tools.Common (in Microsoft.Office.Tools.Common.dll)
Microsoft Office applications do not provide a default UI for users to display custom task panes. If you create a custom task pane in your add-in, you should also create a UI element, such as a button, that users can click to display or hide your custom task pane. For more information, see Custom Task Panes.
The following code example demonstrates an event handler for the event. This event handler updates the state of a toggle button on the Ribbon whenever the user opens or closes the custom task pane. This code example is part of a larger example provided in Walkthrough: Synchronizing a Custom Task Pane with a Ribbon Button.
- Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.