The biggest issue with writing a proper preferences manager with persistent settings is, that Nuke doesn't store default values properly. Example: A checkbox has a default value of 1.0/True. When it is set to this value, the settings file does not include this value, but only the knob itself. So when nuke reads the file the next time, it doesn't know if the 'default' is True or False. To prevent this, the default value can never be nothing, but has to be a specific value, that is written to the file. ## Tested workarounds: ### set nuke.WRITE_ALL flag when saving the file **Failed** As soon as the 'OK' button is clicked in the Settings window, Nuke overwrites the file removing all knobs set to their default. ### force write value to file by check if settings have changed and overwriting the file **Success** Problem: All changes made to custom settings are immideately written to the file. If Nuke crashes there is no way to undo them.