Inheriting from custom window in WPF

Question

I have a custom window in WPF which I want to use as a base window for other windows.
When I tried to inherit it, I wrote in the XAML:

<my:MyWindow x:Class="NewWindow"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:my="clr-namespace:MyNamesapce;assembly=MyAssembly"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">

In the .cs code I wrote:

namespace SomeOtherNamespace
{
    public partial class NewWindow: MyWindow
    {
        internal NewWindow(Control ctrl) : base(ctrl)
        {
            InitializeComponent();
            this.ResizeMode = System.Windows.ResizeMode.NoResize;
        }
    }
}

But then I got the error:

cannot be the root of a XAML file because it was defined using XAML.

What am I doing wrong and how can I fix it?

Answer 1

If what you are trying to achieve is setting ResizeMode to NoResize in every window you could use a style like this:

<Style TargetType="Window" x:Key="windowStyle">
    <Setter Property="ResizeMode" Value="NoResize" />
</Style>

Put this style in a ResourceDictionary and make it be the window style:

Style="{StaticResource windowStyle}"

But if you want to go further you'll have to make a new class inheriting from Window

public class MyWindow : Window
{
    public MyWindow()
    {
        this.ResizeMode = ResizeMode.NoResize;
    }
}

Now you are able to instanciate a new MyWindow

<mn:MyWindow x:Class="Project.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:mn="clr-namespace:MyControls"
        Height="300" Width="300">
</mn:MyWindow>

Be aware the class that will be the "code behind" of this new window need to inherit from your new MyWindow class as below:

namespace Project
{
    public partial class Window1 : MyControls.MyWindow
    {
        public Window1()
        {
            InitializeComponent();
        }
    }
}