Thank you for your reply. From your comments, I know the difference between style attributes and computed style attributes.
I think Mozilla should clarify the sematics about these concepts. This document must answer the following questions:
1. Why: Assigning to the 'height' attribute of a XUL element causes change of the 'height' style attribute, but not vice versa.
The height attribute only specifies one source of the height. Others come from style attributes, included stylesheets, and user and default stylesheets. The actual height is determined by CSS cascading and specificity rules. I think the attribute overrides though. Changing any of the heights shouldn't affect the others. The same is true of various HTML attributes.
getComputedStyle gets the resulting style.
/ Neil
