Control.ProcessKeyPreview Method (Message)


Previews a keyboard message.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
	Flags = SecurityPermissionFlag.UnmanagedCode)]
protected virtual bool ProcessKeyPreview(
	ref Message m


Type: System.Windows.Forms.Message

A Message, passed by reference, that represents the window message to process.

Return Value

Type: System.Boolean

true if the message was processed by the control; otherwise, false.

This method is called by a child control when the child control receives a keyboard message. The child control calls this method before generating any keyboard events for the message. If this method returns true, the child control considers the message processed and does not generate any keyboard events. The m parameter contains the window message to preview. Possible values for the Message.Msg property are WM_CHAR, WM_KEYDOWN, WM_SYSKEYDOWN, WM_KEYUP, and WM_SYSKEYUP. The ProcessKeyPreview method simply sends the character to the parent's ProcessKeyPreview method, or returns false if the control has no parent. The Form class overrides this method to perform actual processing of dialog keys.

Notes to Inheritors:

When overriding the ProcessKeyPreview method in a derived class, a control should return true to indicate that it has processed the key. For keys that are not processed by the control, the result of calling the base class's ProcessKeyPreview method should be returned.


for all windows for inheriting classes to call this method. Associated enumeration: AllWindows value of UIPermissionWindow.


for the immediate caller to call unmanaged code. Associated enumeration: UnmanagedCode

.NET Framework
Available since 1.1
Return to top