我使用来自这个问题的答案的代码来构建我自己的项目菜单。
问题是最顶层的项目应该只有一个图标作为内容。但如果我这样做，则不会显示图标，除非我还设置了 isCheckable=true。
这是我更改的代码。
<ControlTemplate TargetType="{x:Type MenuItem}">
<Border x:Name="Border"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="1">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition x:Name="Col0" MinWidth="17" Width="Auto" SharedSizeGroup="MenuItemIconColumnGroup"/>
<ColumnDefinition Width="Auto" SharedSizeGroup="MenuTextColumnGroup"/>
<ColumnDefinition Width="Auto" SharedSizeGroup="MenuItemIGTColumnGroup"/>
<ColumnDefinition x:Name="Col3" Width="14"/>
</Grid.ColumnDefinitions>
<!-- ContentPresenter to show an Icon if needed -->
<ContentPresenter Grid.Column="0" Margin="4,0,6,0" x:Name="Icon" VerticalAlignment="Center" ContentSource="Icon"/>
<!-- Glyph is a checkmark if needed for a checkable menu -->
<Grid Grid.Column="0" Visibility="Hidden" Margin="4,0,6,0" x:Name="GlyphPanel" VerticalAlignment="Center">
<Path x:Name="GlyphPanelpath" VerticalAlignment="Center" Fill="{TemplateBinding Foreground}" Data="M0,2 L0,4.8 L2.5,7.4 L7.1,2.8 L7.1,0 L2.5,4.6 z" FlowDirection="LeftToRight"/>
</Grid>
<!-- Content for the menu text etc -->
<ContentPresenter Grid.Column="1"
Margin="{TemplateBinding Padding}"
x:Name="HeaderHost"
RecognizesAccessKey="True"
ContentSource="Header"/>
<!-- Content for the menu IGT -->
<ContentPresenter Grid.Column="2"
Margin="8,1,8,1"
x:Name="IGTHost"
ContentSource="InputGestureText"
VerticalAlignment="Center"/>
<!-- Arrow drawn path which points to the next level of the menu -->
<Grid Grid.Column="3" Margin="4,0,6,0" x:Name="ArrowPanel" VerticalAlignment="Center">
<Path x:Name="ArrowPanelPath" HorizontalAlignment="Right" VerticalAlignment="Center" Fill="{TemplateBinding Foreground}" Data="M0,0 L0,8 L4,4 z"/>
</Grid>
<!-- The Popup is the body of the menu which expands down or across depending on the level of the item -->
<Popup IsOpen="{Binding Path=IsSubmenuOpen, RelativeSource={RelativeSource TemplatedParent}}" Placement="Right" x:Name="SubMenuPopup" Focusable="false" PopupAnimation="{DynamicResource {x:Static SystemParameters.MenuPopupAnimationKey}}">
<Border x:Name="SubMenuBorder" BorderBrush="{Binding Path=Foreground, RelativeSource={RelativeSource AncestorType={x:Type Menu}}}" BorderThickness="1" Padding="2,2,2,2">
<Grid x:Name="SubMenu" Grid.IsSharedSizeScope="True">
<!-- StackPanel holds children of the menu. This is set by IsItemsHost=True -->
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Cycle"/>
</Grid>
</Border>
</Popup>
</Grid>
</Border>
<!-- These triggers re-configure the four arrangements of MenuItem to show different levels of menu via Role -->
<ControlTemplate.Triggers>
<!-- Role = TopLevelHeader : this is the root menu item in a menu; the Popup expands down -->
<Trigger Property="Role" Value="TopLevelHeader">
<Setter Property="Padding" Value="6,1,6,1"/>
<Setter Property="Placement" Value="Bottom" TargetName="SubMenuPopup"/>
<Setter Property="MinWidth" Value="0" TargetName="Col0"/>
<Setter Property="Width" Value="Auto" TargetName="Col3"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="Icon"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="GlyphPanel"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="IGTHost"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="ArrowPanel"/>
</Trigger>
<!-- Role = TopLevelItem : this is a child menu item from the top level without any child items-->
<Trigger Property="Role" Value="TopLevelItem">
<Setter Property="Padding" Value="6,1,6,1"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="ArrowPanel"/>
</Trigger>
<!-- Role = SubMenuHeader : this is a child menu item which does not have children -->
<Trigger Property="Role" Value="SubmenuHeader">
<Setter Property="DockPanel.Dock" Value="Top"/>
<Setter Property="Padding" Value="0,2,0,2"/>
</Trigger>
<!-- Role = SubMenuItem : this is a child menu item which has children-->
<Trigger Property="Role" Value="SubmenuItem">
<Setter Property="DockPanel.Dock" Value="Top"/>
<Setter Property="Padding" Value="0,2,0,2"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="ArrowPanel"/>
</Trigger>
<Trigger Property="IsSuspendingPopupAnimation" Value="true">
<Setter Property="PopupAnimation" Value="None" TargetName="SubMenuPopup"/>
</Trigger>
<!-- If no Icon is present the we collapse the Icon Content -->
<Trigger Property="Icon" Value="{x:Null}">
<Setter Property="Visibility" Value="Collapsed" TargetName="Icon"/>
</Trigger>
<!-- The GlyphPanel contains the CheckMark -->
<Trigger Property="IsChecked" Value="true">
<Setter Property="Visibility" Value="Visible" TargetName="GlyphPanel"/>
<Setter Property="Visibility" Value="Collapsed" TargetName="Icon"/>
</Trigger>
<!-- Using the system colors for the Menu Highlight and IsEnabled-->
<Trigger Property="IsHighlighted" Value="true">
<Setter Property="Background" Value="{StaticResource HighlightedBackgroundBrush}" TargetName="Border"/>
<Setter Property="Foreground" Value="{StaticResource HighlightedText}"/>
<Setter Property="BorderBrush" Value="{StaticResource NormalBorderBrush}" TargetName="Border"/>
</Trigger>
<Trigger Property="IsHighlighted" Value="false">
<Setter Property="Background" Value="{StaticResource MenuBackgroundBrush}" TargetName="Border"/>
<Setter Property="Foreground" Value="{StaticResource SolidMenuFontBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource MenuBackgroundBrush}" TargetName="Border"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="LightGray"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
在实际的 UserControl 中，菜单项的使用如下：
<Menu x:Name="myMenu" Grid.Row="0" Grid.Column="1" >
<MenuItem Height="25" Width="30" Header="" IsCheckable="True">
<MenuItem.Icon>
<Image Source="/Tool;component/Resources/help.png" Stretch="Fill" Height="20" Width="20"/>
</MenuItem.Icon>
<MenuItem x:Name="btAbout" Header="About" />
<MenuItem x:Name="btHelp" Header="Documentation" />
<MenuItem x:Name="btBugReport" Header="Bug report" />
<MenuItem x:Name="btFeatureRequest" Header="Feature request" />
</MenuItem>
</Menu>
需要进行哪些更改才能始终显示图标？