As a discipline, I tag all objects I create with the suffix _80 for V8, _70 for V7, _71 for V7.1, etc.
If you do that, you can upgrade and tweak the object in a later version and it won't mess up drawings created in earlier versions.
For example, you could have your custom programmed Window_80, which you subsequently modify as Window_90, and your earlier projects won't get upset because they'll still load Window_80.
To be systematic:
1. When (if) you upgrade to V9, copy all your custom objects to a new folder and change the suffix to _90. Use these for new projects.
2. Archive all of your older projects and save the loaded library objects with them.
3. Tweak and change GDL objects to your hearts content!!
Cheers, Cameron
Cameron Hestler, Architect
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