Restore active preference when reopening window

[DivineDominion]

Closes #16

[SamusAranX]

Safari keeps track of the last opened preference pane even after complete app restarts. Based on a cursory glance, I don't think this does.

[sindresorhus]

We need to check what the Human Interface Guidelines says about that and what other apps do. I would prefer to not have that behavior, personally.

[DivineDominion]

Well:

Restore the last viewed preference pane. If the user switches preference panes, your app should remember this change and show the same pane immediately the next time the user opens your preferences window.
https://developer.apple.com/design/human-interface-guidelines/macos/app-architecture/preferences/

That could mean either.

Restoring state is very broad, too, and says "Preserve and restore your app’s state so people can continue where they left off" and "Configure reopened windows as expected".

But what's expected in terms of preferences? I would not expect the app to restore my last preferences editing session, because I don't do that a lot.

But if an app relies on preferences modifications heavily + requiring restarts, this can get on one's nerves. Does this happen often? At all?

Wouldn't be hard to use UserDefaults to restore the last session, but is that really a use case?

[DivineDominion]

Merged current master into this to make it ready for merging.

Since the HIG aren't clear, I suggest the following:

1. we start with the interpretation that is least invasive/requires the least amount of code change, i.e. restore the session while the app is running (= this PR)
2. we discuss opening the lib for the other interpretation, e.g. adding an option to store the last open tab in the user defaults, and handle that separately

[sindresorhus]

Suggested change

	public func show(preferencePane preferenceIdentifier: PreferencePaneIdentifier? = nil) {
	public func show(preferencePane preferencePaneIdentifier: PreferencePaneIdentifier? = nil) {

?

I think we should be consistent in using preferencePane over just preference.

[sindresorhus]

we start with the interpretation that is least invasive/requires the least amount of code change, i.e. restore the session while the app is running (= this PR)

👍

we discuss opening the lib for the other interpretation, e.g. adding an option to store the last open tab in the user defaults, and handle that separately

I don't think we should do this at all. Most of Apple's apps don't do it, neither does most third-party apps. Instead, I think we should open a Radar to get Apple to clarify in the HIG exactly what's expected with restoring. What do you think?

[DivineDominion]

Found a bug and fixed it :) I'm fine with your verdict @sindresorhus as we can still move on merging this PR and then never talk about restoring the tab after relaunching the app. Works for me :)