I'm having trouble turning off what seems to be the default option to resize my main frame in-game for an addon I'm creating. Anyone know what function I need to call to achieve this?
I have no idea what your Parent Frame actually is. So I'll just guess that you've used AceConfig-3.0 and AceConfigDialog-3.0 to create your own options GUI.....
You can use AceConfigDialog:SetDefaultSize(appName, width, height) to change the default size. But I don't think you can turn off the automatic resizing.