Silverlight 5.0 Custom TextBox: The Tag "TextBox" does not exist in Namespace

Question

I am trying to write my own custom TextBox control in Silverlight 5.

I already have successfully written a custom label control, which I can reuse in my project.

The XAML and the code behind for the label control look like this.

The following code does work for me:

<sdk:Label 

x:Class="Gui.CustomControls.LabelControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:sw="clr-namespace:System.Windows;assembly=System.Windows"
xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
mc:Ignorable="d"
d:DesignHeight="25" d:DesignWidth="125">

<Grid x:Name="LayoutRoot" Background="White">

</Grid>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace Gui.CustomControls
{
    public partial class LabelControl : System.Windows.Controls.Label
    {
        public LabelControl()
        {
            InitializeComponent();

        }


    }
}

Now I want to do the same for a TextBox - writing my own custom TextBox Control. The code for the TextBox looks like this: As you may see, it is nearly the same thing

<sdk:TextBox 

    x:Class="Gui.CustomControls.TextBoxControl"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:sw="clr-namespace:System.Windows;assembly=System.Windows"
    xmlns:controls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls"
    xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
    mc:Ignorable="d"
    d:DesignHeight="25" d:DesignWidth="125">

    <Grid x:Name="LayoutRoot" Background="White">

    </Grid>
</sdk:TextBox>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace Gui.CustomControls
{
    public partial class TextBoxControl : System.Windows.Controls.TextBox
    {
        public TextBoxControl()
        {
            InitializeComponent();

        }



    }
}

While buliding the solution the following error occurs:

"The tag 'TextBox' does not exist in XML namespace 'http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk'"

As the textbox control seems to live in the System.Windows.Controls.TextBox Namespace, I tried different namespaces in the XAML, but nothing worked.

My question is:

Which namespace do I have to use, to build this custom textbox?

If it's not a namespace problem, what am I missing?

Thank you.

Tim S. Tim S. · Accepted Answer · 2012-10-09T11:56:54

It's not sdk:TextBox, just TextBox (i.e. http://schemas.microsoft.com/winfx/2006/xaml/presentation, which is the default xmlns in most XAML files). While oddly not documented on the Silverlight TextBox class, this is documented on the .NET 4.5 TextBox class.

Silverlight 5.0 Custom TextBox: The Tag "TextBox" does not exist in Namespace

1 Answers