When writing editor scripts involving EditorWindow’s it is often important to initialize and cleanup your code when the window is shown and hidden. Specifically it is important to differentiate between the OnDisable and OnDestroy methods if you need to perform some kind of cleanup before the window is closed or disposed of. OnDestroy is called when the user closes the window, where as OnDisable is called after unity recompiles scripts. Think of the OnDestroy method as a close event for the window but the window still resides in memory, where the OnDisable method signals that the window is about to be unloaded from memory such as during a script recompile.

This differentiation is important when you need to save data to disk before the window is destroyed during a recompile. OnDestroy will not get called during recompile only OnDisable does. The OnEnable method is typically intended as a initialization method where you can load data related to the window.

I only wish the Unity team had made these methods more descriptive ala .NET window forms naming scheme. OnDestroy & OnDisable are not the most descriptive for what they do as well as being somewhat similar in spelling. But I digress.