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In this situation the page tabs are most likely hidden in the Visio window settings.
To show the page tabs again when using the Visio Drawing Control (for example, Visio embedded in another application), the hosting application must enable the ShowPageTabs property on the Visio Window object. The relevant code pattern is:
Dim vsoWindow As Visio.Window
Set vsoWindow = DrawingControl1.Window
vsoWindow.ShowPageTabs = True
ShowPageTabs controls whether the page tab controls are visible in the drawing window. When set to True, the page name tabs for all pages in the drawing reappear at the bottom of the window.
If the tabs are intentionally hidden (for example, to show only the white drawing surface), the same property may have been set to False:
vsoWindow.ShowPageTabs = False
Changing it back to True restores the page tabs so all eight pages can be accessed.
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