WPF - Usercontrol height does not size properly - wpf

Question

I have an issue I cannot figure out. I hope I can explain things enough.
Basically, I have a usercontrol that I'm looking to use as a sort of in window modal dialog.
<Grid>
<Rectangle Opacity=".75" Fill="White"/>
<Border Width="425" BorderBrush="LightGray" BorderThickness="2" CornerRadius="20,0,20,0" Padding="3">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="auto"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="auto"/>
<RowDefinition Height="auto"/>
<RowDefinition Height="auto"/>
<RowDefinition Height="15"/>
<RowDefinition Height="auto"/>
</Grid.RowDefinitions>
<!-- First Name -->
<Label Grid.Row="0" Grid.Column="0" Content="First Name:"/>
<TextBox Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="2" Text="{Binding FirstName}" Margin="3"/>
<!-- Last Name -->
<Label Grid.Row="0" Grid.Column="3" Content="Last Name:"/>
<TextBox Grid.Row="0" Grid.Column="4" Grid.ColumnSpan="2" Text="{Binding LastName}" Margin="3"/>
<!-- Address -->
<Label Grid.Row="1" Grid.Column="0" Content="Address:"/>
<TextBox Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="5" Text="{Binding Address}" HorizontalAlignment="Stretch" Margin="3"/>
<!-- City -->
<Label Grid.Row="2" Grid.Column="0" Content="City:"/>
<TextBox Grid.Row="2" Grid.Column="1" Text="{Binding City}" Margin="3"/>
<!-- State -->
<Label Grid.Row="2" Grid.Column="2" Content="State:"/>
<ComboBox Grid.Row="2" Grid.Column="3" ItemsSource="{Binding States}" SelectedValue="{Binding State}" Margin="3"/>
<!-- Zip Code -->
<Label Grid.Row="2" Grid.Column="4" Content="Zip Code:"/>
<TextBox Grid.Row="2" Grid.Column="5" Text="{Binding ZipCode}" Margin="3"/>
<Button Grid.Row="4" Grid.Column="0" Grid.ColumnSpan="6" Width="100" HorizontalAlignment="Center" Content="Save" Command="{Binding SaveCustomerCommand}"/>
</Grid>
</Border>
</Grid>
I also have a resourcedictionary containing a datatemplate to connect this usercontrol to it's viewmodel.
<DataTemplate DataType="{x:Type vm:CreateCustomerViewModel}">
<view:CreateCustomerView/>
</DataTemplate>
Finally, in the main window viewmodel, I create an instance of the control's viewmodel, and in the main window view, I am using an itemscontrol and binding it's itemssource property to the instance of the control's viewmodel.
<ItemsControl Height="600" Grid.Row="0" ItemsSource="{Binding CreateCustomerViewModel}" Grid.RowSpan="2" />
Now, my issue is using the itemscontrol in the main window, I've tried a few different ways, but I cannot get the control to be the height of the window. I'm not sure if I shouldn't be using an itemscontrol, or what I'm doing wrong. Any help is very much appreciated.

Answer 1

ItemsControl is for collections. By default it uses a StackPanel to contain its child elements, which disallows stretching in the stack direction (Vertical by default). For a single item use ContentControl (the base of things like Button and Label) instead:
<ContentControl Height="600" Grid.Row="0" Content="{Binding CreateCustomerViewModel}" Grid.RowSpan="2" />

Answer 2

You could try the following:
Put your ItemsControl in a Grid.
Declare your ItemsControl with VerticalContentAlignment="Stretch".
It shouldn't make any difference because it's the default setting, but declare your ItemsControl with VerticalAlignment="Stretch" and try removing the Height="600".