When creating a UserControl in WPF, I find it convenient to give it some arbitrary Height and Width values so that I can view my changes in the Visual Studio designer. When
In Visual Studio add the Width and Height attribute to your UserControl XAML, but in the code-behind insert this
public UserControl1()
{
InitializeComponent();
if (LicenseManager.UsageMode != LicenseUsageMode.Designtime)
{
this.Width = double.NaN; ;
this.Height = double.NaN; ;
}
}
This checks to see if the control is running in Design-mode. If not (i.e. runtime) it will set the Width and Height to NaN (Not a number) which is the value you set it to if you remove the Width and Height attributes in XAML.
So at design-time you will have the preset width and height (including if you put the user control in a form) and at runtime it will dock depending on its parent container.
Hope that helps.