Mislabeled buttons - Thunderbird
From MozillaZine Knowledge Base
This article documents buttons that are mislabeled (i.e. lie about what they actually do).
Check for Updates
The Check for Updates button does not just check for updates. If it finds one it downloads an update regardless of your settings  . A similar problem occurs with Firefox  but this problem is due to Thunderbird specific code in the About Thunderbird dialog window, not shared application update code.