Dropdown Menu in WPF Toolbar
You could try placing a Menu & MenuItem inside the Toolbar. I've had to use Menu's and MenuItem trees in various parts of the interface (besides classical menus) to get the dropdown menu behavior. You can tweak the control template of the menu to sculpt the look and feel to look however you like and completely abandon the vanilla menu look and feel.
Here's some XAML to show a simple implementation:
<Window x:Class="Window1"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"Title="Window1" Height="300" Width="300"><StackPanel> <ToolBar> <Button Content="Button1"></Button> <Button Content="Button2"></Button> <Menu> <MenuItem Header="Menu"> <MenuItem Header="MenuItem1"/> </MenuItem> </Menu> </ToolBar></StackPanel>