In the Moderator Control Panel (MCP), you can view and edit any topic, notably by going to viewtopic.php and then clicking to "MCP" link (template file used: mcp_topic.html).

You can display posts from previous X days. If you choose "7 days" (for example) and there is no post added during the last week, you won't see any error message such as "No posts exist inside this topic for the selected time frame". Doing the same action in viewtopic.php and you see that error message. Moreover, the action <select> and the links (un)mark all are useless if there is no displayed post at all.