In many interfaces, there is a set of default settings and then a need for the user to be able to override those with custom settings. Do you have any examples of how to handle this well in an interface? I'm thinking mainly about web forms.
Another way to put this is: "How to inherit settings for configurations?"
There are two reasons for making something like this: 1) Hiding the custom options by default simplifies the form 2) The default options can be coming from somewhere else (maybe project-specific settings), and if you don't have any custom settings set, updating the default value will affect all the items with the default settings.
I feel that a good solution would have the following properties: 1) It should be clear whether you have custom or default settings active 2) You should be able to easily go back from custom settings to the defaults
Also, there is the question, whether to show the custom settings to users that have default settings active or not.
A) I found a couple of examples with quick googling, all of them are more-or-less glorified radio-buttons that toggle the custom part of the form:
B) Another option would be to have the custom form always visible but to have a "reset" button to reset the form back to the default state with maybe a label showing that you have customised some of the settings.
C) A third approach would be similar to A but with checkbox saying "link this item to the global settings" (essentially the opposite checkbox state from the check boxes / radio buttons in A). This would be similar to the "use global light" setting in Photoshop: