When I’m editing things in say, the Project Security settings window or the properties window of a widget, I’ll sometimes accidentally close the window by pressing X instead of OK. This immediately closes the window and disregards any changes I’ve made. This makes sense, I don’t think the changes should be applied until OK is pressed. But I think it could be helpful to have a pop-up saying “Are you sure?” or “Save changes?” when closing the window without pressing OK to minimise the risk of accidentally losing changes.