Binding with ElementName in Style setter - wpf

Question

I have a base style for Button which contains the ControlTemplate, then I want to create a few styles based on that which just set the Content for commonly used things like "OK", "Cancel", etc.
In those styles I have an image followed by some text, and I want to bind the height of the image to the height of the text, so I've got the following:
<Style x:Key="OkayButtonStyle" TargetType="{x:Type Button}" BasedOn="{StaticResource RoundedButtonStyle}">
<Setter Property="Content">
<Setter.Value>
<Grid HorizontalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Image Grid.Column="0" Source="{DynamicResource OkayIcon}" Height="{Binding ActualHeight, ElementName=ButtonText}"/>
<TextBlock x:Name="ButtonText" Grid.Column="1" Margin="5,0,0,0" Text="Okay"/>
</Grid>
</Setter.Value>
</Setter>
</Style>
Doing that gives me the error:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=ButtonText'. BindingExpression:Path=ActualHeight; DataItem=null; target element is 'Image' (Name=''); target property is 'Height' (type 'Double')
I'm guessing it's trying to find ButtonText in the ControlTemplate which it obviously can't. Is there a way to accomplish what I'm trying to do here and bind to another element's property from within this style setter?

Answer 1

I don't know why that binding is not working for you; perhaps because name resolution visual tree something or other.
But this works for me, and also addresses the shared-resource issue I mentioned in comments.
<DataTemplate x:Key="ButtonContent" >
<Grid HorizontalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Image
Grid.Column="0"
Source="{DynamicResource OkayIcon}"
Height="{Binding ActualHeight, ElementName=ButtonText}"
/>
<TextBlock
x:Name="ButtonText"
Grid.Column="1"
Margin="5,0,0,0"
Text="Okay"
FontSize="32"
/>
</Grid>
</DataTemplate>
<Style
x:Key="OkayButtonStyle"
TargetType="{x:Type Button}"
BasedOn="{StaticResource RoundedButtonStyle}"
>
<Setter Property="ContentTemplate" Value="{StaticResource ButtonContent}" />
</Style>