SourceName with MultiTriggers - wpf

Question

Is it possible to use a MultiTrigger to evaluate properties on multiple elements? That don't reside within a template, but are within the Usercontrol/Window.
Example:
<CheckBox x:Name="checkBox1" />
<CheckBox x:Name="checkBox2" />
<CustomControl>
<CustomControl.ContentTemplate>
<DataTemplate>
<DataTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition
SourceName="checkBox1"
Property="IsChecked"
Value="False" />
<Condition
SourceName="checkBox2"
Property="IsChecked"
Value="True" />
</MultiTrigger.Conditions>
<MultiTrigger.Setters>
<Setter
Property="Visibility"
Value="Collapsed" />
</MultiTrigger.Setters>
</MultiTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</CustomControl.ContentTemplate>
In a normal Trigger we can use the sourceName to trigger against properties on either of those checkbox controls, but with a MultiTrigger I get build errors when it attempts to find those controls.
Note: The reason I'm using a DataTemplate as opposed to a Style is mentioned here

Answer 1

You can indeed use source name, but your DataTemplate doesn't appear to be defined correctly. I've tried filling out your example which seems to work:
<Page
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:sys="clr-namespace:System;assembly=mscorlib">
<Grid>
<Grid.Resources>
<DataTemplate DataType="{x:Type sys:String}">
<StackPanel>
<TextBlock x:Name="textBlock" Text="{Binding}"></TextBlock>
<CheckBox x:Name="checkBox1" />
<CheckBox x:Name="checkBox2" />
</StackPanel>
<DataTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition
SourceName="checkBox1"
Property="IsChecked"
Value="False" />
<Condition
SourceName="checkBox2"
Property="IsChecked"
Value="True" />
</MultiTrigger.Conditions>
<MultiTrigger.Setters>
<Setter
TargetName="textBlock"
Property="Visibility"
Value="Collapsed" />
</MultiTrigger.Setters>
</MultiTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</Grid.Resources>
<ContentControl>
<sys:String>Foo</sys:String>
</ContentControl>
</Grid>
</Page>
The problem appears to be that you don't define your CheckBoxes inside your DataTemplate, which is where they need to be.