WPF 菜单背景与标题重叠

如何解决WPF 菜单背景与标题重叠

菜单的背景出现在标题上方。 menu with colour background

将背景设置为透明可解决此问题，但会导致存在分隔符的地方出现透明间隙。 menu with transparent background

请注意，我使用的是 MaterialDesign。

<Menu Background="Transparent"
                      Foreground="LightGray"
                      FontWeight="normal"
                      Height="25"
                      FontSize="13">
                    <MenuItem Header="File"
                              Height="25"
                              Width="Auto">
                        <MenuItem Header="Exit"
                                  BorderThickness="0"
                                  Background="#303030"
                                  Command="{Binding ExitCommand}" />
                    </MenuItem>
                    <MenuItem Header="TIA"
                              Height="25"
                              Width="Auto">
                        <MenuItem Header="Start TIA portal"
                                  Background="#303030"
                                  Command="{Binding StartPortalCommand}"
                                  Icon="{materialDesign:PackIcon Kind=Link}" />
                        <MenuItem Header="dispose TIA portal"
                                  Background="#303030"
                                  Command="{Binding disposePortalCommand}"
                                  IsEnabled="{Binding HasPortal}"
                                  Icon="{materialDesign:PackIcon Kind=LinkOff}" />
                        <Separator />
                        <MenuItem Header="Add external Source"
                                  Background="#303030"
                                  Command="{Binding AddExternalSourceCommand}"
                                  IsEnabled="{Binding HasProject}"
                                  Icon="{materialDesign:PackIcon Kind=FilePlusOutline}" />
                        <Separator />
                        <MenuItem Header="Open project"
                                  Background="#303030"
                                  Command="{Binding OpenProjectCommand}"
                                  Icon="{materialDesign:PackIcon Kind=FolderOpenOutline}" />
                        <MenuItem Header="Save project"
                                  Background="#303030"
                                  Command="{Binding SaveProjectCommand}"
                                  IsEnabled="{Binding HasChanges}"
                                  Icon="{materialDesign:PackIcon Kind=ContentSaveOutline}" />
                        <MenuItem Header="Close project"
                                  Background="#303030"
                                  Command="{Binding CloseProjectCommand}"
                                  IsEnabled="{Binding HasProject}" />
                    </MenuItem>
                </Menu>