In a page with a gallery if the user copies the source content of the gallery section and then clicks on a url that exists as a label for a gallery content, then the link is opened in the same tab as Special:CX. If the page has been recently saved then no warning is displayed. If the page has unsaved changes then a warning is displayed. After being taken to the linked page, if the user uses the previous/back option from the browser to return to Special:CX then the copied over gallery section appears empty.
Tested while translating https://en.wikipedia.org/wiki/Torre_Latinoamericana from English to Bangla.