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TextBox Class

Updated: February 2009

Represents a control that can be used to display or edit unformatted text.

Namespace:  System.Windows.Controls
Assembly:  PresentationFramework (in PresentationFramework.dll)

public class TextBox : TextBoxBase, IAddChild

Content Model: A TextBox can contain only unformatted text. See TextBox Content Model Overview for more information.

The following graphic shows an example of a TextBox.

Example of a TextBox

TextBox screen shot

TextBox is a composite control that is composed of several encapsulated components. Consequently, some events do not bubble up to the containing control because they are handled by encapsulated child elements. Because of this, application developers should listen for the tunneling version of an event (denoted by the prefix "Preview").

TextBox supports unformatted text only. For applications that require support for richer content, see RichTextBox. For applications that need to accept passwords or other sensitive input, see PasswordBox.

Horizontally and vertically aligning text within a TextBox is done with the HorizontalContentAlignment and VerticalContentAlignment properties. Aligning the TextBox within the layout of the page is done with the HorizontalAlignment and VerticalAlignment properties.

The best way to hide the border around a TextBox is to set the BorderThickness property of the TextBox to 0.

Important noteImportant Note:

TextBox has built-in handling for the bubbling  MouseUp and MouseDown events. Consequently, custom event handlers that listen for MouseUp or MouseDown events from a TextBox will not be called. If you need to respond to these events, listen for the tunneling PreviewMouseUp and PreviewMouseDown events instead, or register the handlers with the HandledEventsToo argument (this latter option is only available through code). Do not mark the event handled unless you deliberately want to disable TextBox native handling of these events, and be aware that this has notable effects on the control's UI.

Scrollbars are not visible on a TextBox by default. To make scrollbars visible, set the VerticalScrollBarVisibility and HorizontalScrollBarVisibility properties to Visible or Auto.

Usually the TextChanged event should be used to detect whenever the text in a TextBox or RichTextBox changes rather then KeyDown as you might expect. See How to: Detect When Text in a TextBox Has Changed for an example.

Dependency properties for this control might be set by the control’s default style. If a property is set by a default style, the property might change from its default value when the control appears in the application. The default style is determined by which desktop theme is used when the application is running. For more information, see Themes.

This example shows one way to use the SelectedText property to retrieve text that the user has selected in a TextBox control.

The following Extensible Application Markup Language (XAML) example shows the definition of a TextBox control that contains some text to select, and a Button control with a specified OnClick method.

In this example, a button with an associated Click event handler is used to retrieve the text selection. When the user clicks the button, the OnClick method copies any selected text in the textbox into a string. The particular circumstances by which the text selection is retrieved (clicking a button), as well as the action taken with that selection (copying the text selection to a string), can easily be modified to accommodate a wide variety of scenarios.

<TextBox Name="tbSelectSomeText">
  Some text to select...

<Button Click="OnClick">Retrieve Selection</Button>

The following C# example shows an OnClick event handler for the button defined in the XAML for this example.

void OnClick(object sender, RoutedEventArgs e)
    String sSelectedText = tbSelectSomeText.SelectedText;

More Code

How to: Set the Text Content of a TextBox Control This example shows how to use the Text property to set the initial text contents of a TextBox control.
How to: Set Focus in a TextBox Control This example shows how to use the Focus method to set focus on a TextBox control.
How to: Detect When Text in a TextBox Has Changed This example shows one way to use the TextChanged event to execute a method whenever the text in a TextBox control has changed.
How to: Position the Cursor at the Beginning or End of Text in a TextBox Control This example shows how to position the cursor at the beginning or end of the text contents of a TextBox control.
How to: Use a Custom Context Menu with a TextBox This example shows how to define and implement a simple custom context menu for a TextBox.
How to: Aid Usability of a TextBox Using a Background Image The following example shows how to aid usability of a TextBox by displaying an explanatory background image inside of the TextBox until the user inputs text, at which point the image is removed. In addition, the background image is restored again if the user removes their input. See illustration below.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0




February 2009

Described how default styles change dependency properties.

Customer feedback.

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