Pausing TextureImporter with a Popup window and waiting for user input

I’m wondering if there’s a way to pause the TextureImporter from continuing on from OnPreprocessTexture() to OnPostprocessTexture() so I can pop up a GUI window that allows you to adjust some of the settings for the textures to be imported (i.e.: texture size), and wait for a user to press “accept” before continuing on with the importing. The idea being to allow us to change Texture settings on the fly with each import.

I’ve tried multiple ways to do this, primarily using StartAssetEditing() and StopAssetEditing() within OnPreprocessTexture and OnPostprocessTexture, but it mostly just seems to lock up Unity. Since I can’t run coroutines in the TextureImporter functions, I’m not sure of a lot of ways to do this, besides importing everything, changing the settings, then re-importing.

Is this kind of functionality possible?

No, the importing process is done in one run and can’t be suspended. Everytime Unity would reimport a texture it would start your postprocessor. It’s better to store those settings somewhere and use them during import. Do it like the TextureImporter itself: If you change any settings it have to reimport the texture (when pressing apply).