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Once you're satisfied that a particular warning or a particular class of warnings does not matter, you can hide that warning or similar warnings by right clicking the message and choosing "Suppress".
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The amount of warnings that you get in a typical compilation is almost unbearable. The supress manager helps a bit, but it is not a real solution. What you usually would want to supress is not a specific type of warning, but specific occurences of the warning.
Quartus can also hide warning at the module level, but it is not good enough. What I would like is an attribute to specify something like "don't warn me about this specific signal being stuck at GND", but keep warning me about other signals.