oqtane.framework/Oqtane.Client/Modules/Controls/TabControl.razor

@namespace Oqtane.Modules.Controls
@inherits ModuleBase

<CascadingValue Value="this">
    <div>
        @foreach (TabPanel tabPanel in _tabPanels)
        {
            <button type="button"
                    class="btn @GetButtonClass(tabPanel)"
                    @onclick=@( () => ActivateTabPanel(tabPanel) )>
                @tabPanel.Text
            </button>
        }
    </div>
    @ChildContent
</CascadingValue>

@code {
    // Next line is needed so we are able to add <TabPanel> components inside
    [Parameter]
    public RenderFragment ChildContent { get; set; }

    public TabPanel ActiveTabPanel { get; set; }
    List<TabPanel> _tabPanels = new List<TabPanel>();

    internal void AddTabPanel(TabPanel tabPanel)
    {
        _tabPanels.Add(tabPanel);
        if (_tabPanels.Count == 1)
            ActiveTabPanel = tabPanel;
        StateHasChanged();
    }

    string GetButtonClass(TabPanel tabPanel)
    {
        return tabPanel == ActiveTabPanel ? "btn-primary" : "btn-secondary";
    }

    void ActivateTabPanel(TabPanel tabPanel)
    {
        ActiveTabPanel = tabPanel;
    }
}