Comment 15 for bug 494772

Yesterday, responsibility for specifying the software updates design was shunted back to me. So, here's the relevant part of my specification-in-progress:
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Whenever the computer is running on battery, there should be an item [of text at the bottom of the main updates window, just above the “Cancel” and “Install Now” buttons] (fixing bug 484249 and bug 494772) with exactly the same battery icon as the power status menu <https://wiki.ubuntu.com/PowerStatusMenu> is currently using for the battery, and the text: “It’s safer to connect the computer to AC power before installing.” (fixing bug 426708). The item should automatically appear or disappear (with the alert resizing appropriately) if the computer starts or stops using battery while the alert is open (fixing bug 426710).
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This way, the battery warning wouldn't interrupt anything, because it's not a separate alert. But Update Manager would still appear automatically, even if you were using battery at the time. I'm interested in suggestions of a way of delaying automatic opening if your computer happens to be using battery, without starving people of updates when they *only* ever run their computer on battery. (And without adding more settings!) In the meantime, maybe someone would like to implement what I've written above to see if it looks and feels reasonable.