Update: Please note that if you do this in a version of GM which does not have tabbed scripts, such as 1.3.1335, you will get back one long script which is safe to use, rather than separated scripts like you do in EA97.
Starting with the April Early Access release, the GameMaker: Studio script editor has the functionality to add 'Tabs' and 'Bookmarks' into your scripts.
This causes projects with tabs/bookmarks to add some additional information into those script resources. When this project is brought back into earlier versions of GM: S, that information is displayed as #define 'FUNCTION/TAB NAME' and pushes all tabs into one long script.
There is a simple way to remove all unwanted information and separate the tabs out into individual script resources (and is much safer than just deleting the unwanted lines and carrying on - which may result in a loss of part of your script, so please don't do that):
- Open the project with tabs in the old version of GM:S
- Delete all of the script resources
- Right click on the Scripts folder and select Add Existing Script
- Navigate to the project folder \scripts and add in all .gml files
- This will add all tabs as separate resources and remove any unwanted extra information