http://www.xulplanet.com/tutorials/xultu/titledbox.html http://www.xulplanet.com/reference/elemref/ref_caption.html A header for a groupbox. It may contain either a text label, using the label attribute, or child elements for a more complex caption. This should be set to a letter that is used as a shortcut key. This letter should be one of the characters that appears in the label text for the caption. This letter will typically be drawn underlined, although this behavior will be platform and theme specific. When the user presses ALT (or a similar key that varies on each platform) and the access key, the caption will be activated from anywhere in the window. Although the value is case insensitive, a letter with the case matching the accesskey attribute will used if both cases exist in the label. If the label of the caption is too small to fit in its given space, the text will be cropped on the side specified by the crop attribute. An ellipsis will be used in place of the cropped text. If the box direction is reversed, the cropping is reversed. The text will be cropped on its left side. The text will be cropped on its right side. (Deprecated) The text will be cropped on its left side. (Deprecated) The text will be cropped on its right side. The text will be cropped on both sides. The text will be not be cropped using an ellipsis. However, the text will simply be cut off if it is too large. The side depends on the CSS text alignment. The URL of the image to appear on the caption. If this is attribute is left out, no image appears. The position of the image is determined by the dir and orient attributes. The label that will appear on the caption. If this is left out, no text appears. The tab order of the element. The tab order is the order in which the focus is moved when the user presses the Tab key. Elements with a higher tabindex are later in the tab order sequence.