Programmatically hide dashboard Tabs

This is the simplest approach (there are others).

Have a "Layout" dashboard of type Embedded Dynamic Repeater, with Layout Type set to Tabs.

Have your other dashboards of type Embedded

Create a Component "TabTemplate" of type Embedded Dashboard, and set a variable in the Embedded Dashboard property.

Assign that component to the Layout dashboard

Now create your "MyTabAssembly" assembly, containing a Dynamic Dashboard Service "MyDynDashService".

This is the core of the technique: in the GetEmbeddedDynamicDashboard method, manipulate the ComponentTemplateRepeatItems list to define items; for each item, the variable we used in our Embedded Dashboard component will be populated to point to a particular dashboard.

Public Function GetEmbeddedDynamicDashboard(ByVal si As SessionInfo, ByVal api As IWsasDynamicDashboardsApiV800, ByVal workspace As DashboardWorkspace, _
            ByVal maintUnit As DashboardMaintUnit, ByVal parentDynamicComponentEx As WsDynamicComponentEx, ByVal storedDashboard As Dashboard, _
            ByVal customSubstVarsAlreadyResolved As Dictionary(Of String, String)) As WsDynamicDashboardEx Implements IWsasDynamicDashboardsV800.GetEmbeddedDynamicDashboard
            Try
                If (api IsNot Nothing) Then
					If storedDashboard.Name.XFEqualsIgnoreCase("Layout") Then
						' get the dashboard
						Dim layoutDashboard = api.GetEmbeddedDynamicDashboard(si, workspace, parentDynamicComponentEx, storedDashboard, String.Empty, Nothing, TriStateBool.Unknown, WsDynamicItemStateType.Unknown)
						' build an item definition with suffix and variable values
						Dim newTab = New XFDynamicDashboardTemplateItemDefinition("t1", "d=Tab_1")
						' manipulate the list 
						layoutDashboard.DynamicDashboard.ComponentTemplateRepeatItems.Add(newTab)
						' return the dashboard
						return layoutDashboard
					Else
                    	Return api.GetEmbeddedDynamicDashboard(si, workspace, parentDynamicComponentEx, storedDashboard, String.Empty, Nothing, TriStateBool.Unknown, WsDynamicItemStateType.Unknown)
					End If
                End If

                Return Nothing
            Catch ex As Exception
                Throw New XFException(si, ex)
			End Try
        End Function

To clarify, and if you want to test manually before using code, this snippet is manipulating this property on the Layout dashboard:

Effectively doing the same as:

Now create your Service Factory and enable your service as usual

Execute it in Designer mode, and you'll see that the dashboard includes your tab.

If you want more tabs, just add (or remove) items from that ComponentTemplateRepeatItems list. If you want to drive it with Parameters (e.g. the number of tabs, or anything else), you will find them in the customSubstVarsAlreadyResolved dictionary.