User Interface - OK/Cancel/Apply

[ChrisGreaves]

I think I asked this recently but cannot find it in YourPosts, so here, at least, it gets a topic title.

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When I am exploring a new feature I tend to run through a set of options all at once. In the example screenshot I am toggling switches in two panes related to Servers. I find a similar situation when presented with related panes in, for example, Tools, Options, Indexing.
I understand how the OK and the Cancel buttons operate (I think)
Cancel: Please just get me out of here; abandon any outstanding changes and exit the interface.
OK: I am done now; please save any outstanding changes on any related panes and exit the interface.

Apply: I thought I knew what this did, but am no longer sure.
Save outstanding changes to this pane and continue in this pane. But if I change to another pane, are my outstanding changes discarded?
Save all outstanding changes to any pane I have visited on loading this interface. This would imply that I can flip between two or more panes and Everything will retain the edits made to each pane until I
(a) Preserve all outstanding changes with Apply and continue editing
(b) Preserve all outstanding changes with OK and exit the interface
(c) Exit the interface (Cancel) discarding any outstanding changes.

I have run a couple of tests to see what happens, but I'd love to have a definitive statement of what is supposed to happen as a consequence of using, or of not using, the Apply button throughout the Everything user interface system
Thanks, Chris

[void]

Apply = Apply all changes (in all tabs) and keep the options dialog opened.

[ChrisGreaves]

Apply = Apply all changes (in all tabs) and keep the options dialog opened.

Thank you Void.