Original report at SourceForge, opened Tue Feb 8 16:27:19 2011

savefig does not issue a warning on a non-existent keyword name

Example
Savefig('filename.png', NonExistant=True)
Will not throw any warning. This is especially important if you accidentally misspell an argument, such as:
Savefig('filename.png', tranperent=True)
Notice 'transperent' instead of 'transparent'