RichTextBox.OnMouseLeftButtonDown Method
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Called before the MouseLeftButtonDown event occurs.
Namespace: System.Windows.Controls
Assembly: System.Windows (in System.Windows.dll)
Syntax
'Declaration
Protected Overrides Sub OnMouseLeftButtonDown ( _
e As MouseButtonEventArgs _
)
protected override void OnMouseLeftButtonDown(
MouseButtonEventArgs e
)
Parameters
- e
Type: System.Windows.Input.MouseButtonEventArgs
The data for the event.
Remarks
The OnMouseLeftButtonDown method is called before any event handler for the MouseLeftButtonDown event is called. This method allows derived classes to handle the MouseLeftButtonDown event without attaching a delegate. This is the preferred technique for handling the event in a derived class.
The RichTextBox implementation marks the MouseLeftButtonDown event as handled by setting the Handled property of the event data to true.
RichTextBox handles cursor placement and selection in MouseLeftButtonDown event. RichTextBox attempts to capture the mouse in its MouseLeftButtonDown event handler. Mouse capture is needed for extending the selection by using the mouse. Mouse capture is released in the RichTextBox's MouseLeftButtonUp event handler. If you capture the mouse on another UIElement's MouseLeftButtonDown handler, extending the selection by using a mouse in the RichTextBox control will not work.
Derived classes can prevent the RichTextBox from processing the MouseLeftButtonDown event by setting the Handled property of the event data to true.
Notes to Inheritors
When overriding the OnMouseLeftButtonDown method in a derived class, be sure to call the base class’s OnMouseLeftButtonDown method so that registered delegates receive the event.
Version Information
Silverlight
Supported in: 5, 4
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.