The ChildKeyDown event is triggered whenever OpenROAD receives a WM_KEYDOWN or WM_SYSKEYDOWN message. The event is not queued, but is generated immediately.

Information about the key is stored in a KeyDownData object, which is delivered to the 4GL program in the MessageObject attribute of the FrameExec. The 4GL event code has the opportunity to stop further processing of the WM_KEYDOWN or WM_SYSKEYDOWN message by modifying the KeyDownData object. To discard the message, set the KeyDownData.VirtualKey to zero. The PrintScrn key does not cause a ChildKeyDown event and no other events are generated in conjunction with a ChildKeyDown event.