Unfortunately, the wikis don't show much information beyond a physical description of what the corpse containers are, and what they do:
Dead bodies are a type of container holding potential treasure. […] Clicking a dead body will move it slightly and reveal any items or gold that was hidden on it.
Corpses: The bodies of fallen warriors often ...
Right click on the settings window to close it. You have to right click on the top part of the window, even on the "SETTINGS" part itself would work.
You can also drag the window around, it doesn't have to always be in the upper left area.