Language Reference Guide > Language Reference Guide > System Classes > MouseData Class > CancelEvent Attribute
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CancelEvent Attribute
Data Type: integer
4GL Access: RW
You can intercept a mouse down message and prevent further processing of a WM_LBUTTONDOWN, WM_MBUTTONDOWN, or WM_RBUTTONDOWN message by setting the CancelEvent attribute to TRUE in the MouseDown or ChildMouseDown event block.
In the following example, generation of any 4GL event that would happen because of this particular mouse down event will not occur:
On ChildMouseDown =
Declare
    MouseInfo = MouseData default NULL;
Enddeclare
Begin
    MouseInfo = MouseData( CurFrame.MessageObject );
    /* Do no further processing as a result of this ChildMouseDown event */
    MouseInfo.CancelEvent = TRUE;
End;
Setting the CancelEvent attribute in a MouseUp event block is not applicable to this event and, although a legal OpenROAD statement, it has no effect on the application.
Last modified date: 06/25/2024