I'm using Leviathan template, by default, the system message like "login failed" or "You need to register first" will show up in Drawer position. I want them to be displayed in the main body, like an article, but not in any module positions. If it shows up in a pop-up message box/panel/window, it's also acceptable.
You will have to change the way Joomla core works or find suitable joomla plugin on JED. This is not something that can be achieved by handling template config (except if you want to just move drawer position in some other module position)