Thule_Debug::action(); // default same as 0
Thule_Debug::action(DEBUG_PRINTR);
Thule_Debug::action(DEBUG_VARDUMP);
Thule_Debug::action(DEBUG_POPUP);
If you put the dump function to anywhere, you can see the query (and optional class) in bottom of your page.
Thule_Debug::dump();
echo $Frontend->debug();