Auto-save in GMEdit is a slightly tricky subject since some of the syntax extensions result in code editor updates (like the JSDoc auto-generator) or project structure (like #lambda for <=2.2) changes, making it non-preferable to save the file without explicit consent. In combination with this, most GMEdit features (like syntax checking or updating auto-completion information) trigger after a successful save operation. "Auto-save every X minutes but only if you are not using any of the following features that define the editor" doesn't sound very good.