Add placebo button to Options dialogs

[hinerm]

I was showing @bnorthan how to turn image synchronization on and he asked if people get confused by the lack of an "OK" button in dialogs. Personally, this bothers me and I think it is a definite possibility. I feel like options dialogs could just automatically add a placebo button to close the dialog, and that would help people psychologically.

[ctrueden]

The OS X standard for these dialogs is no OK button, while the Windows standard is OK/Cancel/Apply. We could generalize this into some platform-specific logic which we lean on in various places.

However, I am against a placebo. It might help people feel safe, but the feeling would be an illusion—checking a box does instantly change the option, which might have immediate effects on subsequent operations even before closing the dialog box. And clicking the red X to close the window would not cancel any changes which had been previously made.

So if we decide to add OK/Cancel/Apply on some (or all) OSes, we should do the work to make the changes only go into effect when you actually click OK and/or Apply.

[hinerm]

We could instead do something like Discourse does when changing configuration settings. As you alter values, little Undo/OK buttons pop up. We don't want buttons if the changes take effect right away, but maybe we could at least give some visible feedback - like the row itself turns red or green to signify the option is enabled/disabled.

So yeah, I agree that a placebo button itself may not be the right thing here.. but I don't think visual feedback would hurt.