true to consume the key; false to allow further processing.
This method is called during message pre-processing to handle dialog characters, such as TAB, RETURN, ESCAPE, and arrow keys. This method is called only if the isInputKey method indicates that the control isn't interested in the key. processDialogKey simply sends the character to the parent's processDialogKey method, or returns false if the control has no parent. The Form class overrides this method to perform actual processing of dialog keys. When overriding processDialogKey, a control should return true to indicate that it has processed the key. For keys that aren't processed by the control, the result of base.processDialogChar should be returned. Controls will seldom, if ever, need to override this method.