Can we please add a dialog-popup that asks "Are you sure you want to close this map?" (see attachment) I had one instance where I accidentally clicked the X (close) trying to organize my tabs. I could've just closed my whole project without saving and then reopen it but I had other elements that I needed to save before closing the project. With as many users in our organization I have a feeling this issue will come up more often.
Closing your map will not undo or remove any of your changes. To reopen your map, go to the Catalog pane > Project tab. Expand the Maps group and double-click your map to reopen it. You can also right-click and choose Open.
It will still have any changes that you made before you closed the map, even if you did not click the Save button first.
If this is still a feature that you need, you can log the request in ArcGIS Ideas.