<?xml version="1.0"?> <window xmlns:html="http://www.w3.org/1999/xhtml" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> <hbox flex="1"> <html:style> /* Make sure our splitter's background doesn't depend on its hover styles */ splitter { background-color: yellow; -moz-appearance: none; } </html:style> <splitter collapse="before" resizeafter="farthest" width="200" id="s"> </splitter> </hbox> </window>