CODE EXAMPLE FOR CSHARP

wpf toolbar disable overflow

<ToolBarPanel DockPanel.Dock="Top">
    <ToolBar ToolBarTray.IsLocked="True" Loaded="ToolBar_Loaded">
        <Menu ToolBar.OverflowMode="Never">
            <MenuItem Header="File" />
            <MenuItem Header="New" />
        </Menu>
    </ToolBar>
</ToolBarPanel>