Why is canCheckForUpdates enabled while sessionInProgress?

[pilotmoon]

I noticed that Sparkle sets canCheckForUpdates to YES even when sessionInProgress is YES. This appears to be tied to the statement in docs:

An update check can be made by the user when an update session isn't in progress, or when an update or its progress is being shown to the user.

(my emphasis)

But I'm curious why canCheckForUpdates is enabled while something is being displayed to the user, even if session in progress?
The docs clearly say we should be validating UI state against canCheckForUpdates and not sessionInProgress. But attempting to actually call checkForUpdates: while a session is progress always fails with Error: -checkForUpdates called but .sessionInProgress == YES.

What is the rationale for enabling the "check for updates" button when it won't work?

I'm sure there is a good reason, since it is clearly documented that this is intentional, but it's really baffling me why it works this way.

[zorgiepoo]

It's supposed to be so that if there is UI available to be shown, checking for updates will bring that UI to frontmost focus. Imagine if the update alert window is behind other windows in the app the user is using for example, or if the user driver decided to defer showing the UI immediately.

if (_showingPermissionRequest || _driver.showingUpdate) {
        if ([_userDriver respondsToSelector:@selector(showUpdateInFocus)]) {
            [_userDriver showUpdateInFocus];
        }
        return;
    }

And there are also cases where canCheckForUpdates should be NO while sessionInProgress is YES, like when downloads/update checks are happening in the background automatically, and Sparkle isn't equipped to show UI while this is occurring.

[pilotmoon]

Thank you, that makes a lot of sense, at least when using the standard user driver. I'm going for a slightly different UI approach with an updates UI integrated into the app window. Since it's always in front there nothing "bring to the front". But I think I can just bind to sessionInProgress instead to get the desired behaviour. Thanks for the fast reply.

[zorgiepoo]

In the future we can consider making showUpdateInFocus optional which I think would make this case be better integrated #2704