Simon Brüchner recommended: > http://piro.sakura.ne.jp/xul/_contentholder.html.en I don't know that contentholder will do the trick, but on the same page, there is a link to http://piro.sakura.ne.jp/xul/ _ezsidebar.html.en, which apparently does exactly what I want: to undock sidebars. Thanks for the tip! Dave land=