Question

I’m searching for a way to create a global resource for all windows in my WPF project.
I have various windows with different controls but they should all have the same context menu e.g this context menu for a button:

        <Button.ContextMenu>
            <ContextMenu>
                <MenuItem Header="1"/>
                <MenuItem Header="More">
                    <MenuItem Header="2"/>
                    <MenuItem Header="2" IsCheckable="True"/>
                    <MenuItem Header="2" IsCheckable="True"/>
                    <MenuItem Header="2" IsEnabled="False"/>
                    <MenuItem Header="More">
                        <MenuItem Header="3"/>
                        <MenuItem Header="More">
                            <MenuItem Header="4"/>
                        </MenuItem>
                    </MenuItem>
                </MenuItem>
            </ContextMenu>
        </Button.ContextMenu>

should also be possible to use on a label in a own different window.

something like this:

resource file: contextMenu
wpf form 1: use contextMenur resource for button
wpf form 2: use contextMenur resource for label
wpf form 3: use contextMenur resource for combobox

all the resource tutorials that I read only had the resource available in the same window

Answer 1

Add it in the App.xaml file, section <Application.Resources>.

<Application ...>
   <Application.Resources>
      <SolidColorBrush x:Key="somebrush" ... />
   </Application.Resources>
</Application>

Somewhere else:

   <Grid Background="{StaticResource somebrush}">
      ...
   </Grid>

(from MCTS Training Kit Windows Applications Development by M.A. Stoecker)

Hence you would put the ContextMenu into the Resources, give it an x:Key, and then write

   <Button ...>
       <Button.ContextMenu>
           <StaticResource ResourceKey="keyThatWasGiven" />
       </Button.ContextMenu>   
   </Button>