Why should I avoid using the CloseButtonClosesWindow property in Office Online?¶
window.close, so in many cases CloseButtonClosesWindow will not behave properly. In such cases
an error may be logged on the browser developer console:
Scripts may close only the windows that were opened by it.
The calling script is not reliably given any information that the
close() call failed, so Office Online can’t detect when
this happens and change behavior. Thus, hosts who wish to close the current window when the Close UI is activated
should prefer to use ClosePostMessage and handle the
UI_Close message for reliable close behavior.