Mouse.PreviewMouseDown Attached Event
Assembly: PresentationCore (in PresentationCore.dll)
XML Namespace: http://schemas.microsoft.com/winfx/2006/xaml/presentation
Which mouse button was depressed is determined by checking the arguments of the event.This is an attached event (using tunneling routing strategy) that is intended through attached event syntax to be referenced by existing user interface (UI) elements that take input.
The Windows Presentation Foundation (WPF) framework builds on this attached event by surfacing it as two different common language runtime (CLR) events on UIElement: PreviewMouseLeftButtonDown and PreviewMouseRightButtonDown. These implementations handle the underlying PreviewMouseDown event and read the arguments of the event to determine whether the left or right mouse button was involved. For three-button, there is no framework-level event support for the center button, and you should use the PreviewMouseDown event and check for the center button condition in the event arguments.
For routed events that relate to the mouse, be careful about how or when you mark them handled. Handling the event near the root and handling it by a child further toward the source may not be appropriate for composited controls, where the compositing pieces might have expected mouse behaviors. The difficulty in making the appropriate choices about whether other elements should also be informed about any given mouse action is in fact why the WPF framework chose the model of having the underlying Mouse routed event be surfaced as CLR events along the route.
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter EditionThe Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.