ButtonBase.OnMouseLeftButtonDown Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Provides class handling for the MouseLeftButtonDown event that occurs when the left mouse button is pressed while the mouse pointer is over this control.

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


Protected Overrides Sub OnMouseLeftButtonDown ( _
    e As MouseButtonEventArgs _
protected override void OnMouseLeftButtonDown(
    MouseButtonEventArgs e



Exception Condition

e is nulla null reference (Nothing in Visual Basic).


This method marks the MouseLeftButtonDown event as handled by setting the MouseButtonEventArgs.Handled property of the event data to true when the button is enabled and its ClickMode is not set to Hover. Since this method marks the MouseLeftButtonDown event as handled in some situations, you should use the Click event instead to detect a button click.

Notes to Inheritors

If you override OnMouseLeftButtonDown, always call the base implementation in your OnMouseLeftButtonDown implementation. Failure to call the base implementation prevents base classes from handling the event with a class handler, which might change the run-time behavior of the final class. You can call the base implementation either before or after your special handling, depending on your requirements.

Version Information


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.