Update notification sometimes prevents input to the rest of the app

When an update notification appears and MailMate is not actively being used, it is possible for MailMate to end up in a state where it will not accept user commands until the notification is dismissed — key commands, clicks on messages, etc all result in an NSBeep and no action taken. This usually happens when the update notification appears while the machine is in Display Sleep (but the machine itself is not sleeping) with MailMate not the foreground app.

This is amplified by the fact that the update window is not shown in Exposé, nor is it shown by hovering on the dock icon when using Hyperdock. Unless the user hides every other app's windows and looks on every Space, it is impossible to find the errant notification window; the easiest resolution is to force quit MailMate (the regular quit command just produces another NSBeep) and restart it. This causes the update notification to appear at the front and be usable.

Would it be possible to have the update notification window show in Exposé, at least? That could provide a workaround as it could be brought to the front and dismissed.