User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20100101 Firefox/17.0 Build ID: 20121128204232 Steps to reproduce: Added content to a panel element until it no longer fit completely on the screen. Actual results: The panel resized dynamically as expected until it was rendered partially off screen, then height and width attributes were added and the panel stopped resizing. Expected results: Height and width attributes should not be added, and the element should resize to fit it's content.
Created attachment 692792 [details] Testcase Testcase to demonstrate the issue. Load the xul file in Firefox 17+ (I've only tested on Windows). Click the Add button multiple times until the panel content goes below the bottom of the screen. Click the Remove button until the content is gone. Compare to FF16.
FTR, see bug 852775 comment 4 which implies the underlying bug is that the 'width' and 'height' attributes are being added unconditionally, when they should only be added when the resize is as a result of the user explicitly resizing. Confirming, updating the title and adding the panel-guru to CC.