The query history menu contains all previously entered queries. Initially this menu is empty. Only queries will appear in this menu, and not input submitted to general Prolog I/O predicates. When you single click on an entry in the query history menu, that entry will replace any text that has already been typed into the query interpreter sub-window. When you double click on an entry, that entry will replace any text that has already been typed into the query interpreter sub-window and the query will be submitted to Prolog. A history menu entry will be compressed into a single line even if it consisted of multiple lines when it was submitted.