As a XUL file is being parsed, if it contains a scale widget with a "min" attribute set to a positive value, then when the widget gets parsed it fires a change event as it sets its value to the value of the "min" attribute. But the widget hasn't really changed, it's just been initialized. So it's misleading to fire this event. The event should be suppressed. Some discussion of the issue is in bug 372047, comment 6, 7, 8, and 9, and there's a testcase demonstrating the problem over in attachment 257306 [details] on that bug.
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