Making the ToolBar Button Style apply to UserControls in the Toolbar
Ooh, my apologies! I misinterpreted your question. Give this a shot:
<Button Style="{StaticResource {x:Static ToolBar.ButtonStyleKey}}"> Hello, world!</Button>The style only targets buttons, so it can only be applied to buttons. (Which won't be a problem by the look of your comment.)
I found a way, that seems to work, although I'm interested in other ways of solving this.
I added a loaded event handler to my UserControl and put this inside it.
if (button.Style == null && this.Parent is ToolBar){ button.Style = (Style)FindResource(ToolBar.ButtonStyleKey);}Where button is the name of the button inside my UserControl.
You would require some powerful black magic in order to get it to create a functioning new style for your usercontrol automatically. There are built-in styles for each type of built-in control that you may add to the toolbar. (Notice that ToolBar.ButtonStyleKey is not alone.) You'll need to craft and apply your own style that matches the standard toolbar elements yourself.