Custom Control Height and Width disappear when resizing in design window - wpf

Question

I've created a WPF Custom Control, I put it on a form and give it a height and a width - all works fine. I'm referencing Height and Width using TemplateBinding in the control, so I need these to be set.
Should I decide to resize the control using the gui, the height and width disappear completely and the control formatting goes wrong.
How do I get the new height and width of the control and set it when this happens?
Posting code as requested:
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:GraphControls">
<Style TargetType="{x:Type local:ContourPlot}" >
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:ContourPlot}">
<Border Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}">
<Grid>
<Viewbox>
<Border BorderBrush="Black" BorderThickness="1">
<Canvas x:Name="cvGraph" Width="{TemplateBinding Width}" Height="{TemplateBinding Height}" >
<Rectangle Canvas.Left="40" Canvas.Top="31" Width="48" Height="41" Fill="AliceBlue"/>
</Canvas>
</Border>
</Viewbox>
<Canvas Width="{TemplateBinding Width}" Height="{TemplateBinding Height}" >
<Label x:Name="lblTest" Canvas.Left="0" Canvas.Top="10" Content="Label" FontSize="12" />
</Canvas>
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Control is used in a form as follows:
<Window x:Class="GraphWrapper.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:gc="clr-namespace:GraphControls;assembly=GraphControls"
Title="MainWindow" Height="350" Width="525">
<Grid>
<gc:ContourPlot Background="#FFC3EAC3" Margin="65,42,128,118" Width="310" Height="150"/>
</Grid>
</Window>
As previously stated, when the control is resized via the gui, the Width and Height properties disappear.

Answer 1

<Style TargetType="{x:Type local:ContourPlot}" >
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:ContourPlot}">
<Border Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Width="{TemplateBinding Width}"
Height="{TemplateBinding Height}">
<Grid>
<Viewbox Width="{TemplateBinding Width}"
Height="{TemplateBinding Height}">
<Border BorderBrush="Black" BorderThickness="1">
<Canvas x:Name="cvGraph" >
<Rectangle Canvas.Left="40" Canvas.Top="31" Width="48" Height="41" Fill="AliceBlue"/>
</Canvas>
</Border>
</Viewbox>
<Canvas >
<Label x:Name="lblTest" Canvas.Left="0" Canvas.Top="10" Content="Label" FontSize="12" />
</Canvas>
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
The Templated width and Height are not recommended to use in multiple controls inside its control Template. In Your case, Height and Width are going to be same as if you set like above.
More over you have placed the ViewBox and the Canvas in same area so its going to be overlap with same width and height. The problem might be with the Viewbox.