Usage of nsIAccessible Interface

 First child in accessible tree

readonly attribute nsIAccessible firstChild

 Focused accessible child of node

readonly attribute nsIAccessible focusedChild

 Last child in accessible tree

readonly attribute nsIAccessible lastChild

 Next sibling in accessible tree

readonly attribute nsIAccessible nextSibling

 Parent node in accessible tree.

readonly attribute nsIAccessible parent

 Previous sibling in accessible tree

readonly attribute nsIAccessible previousSibling

 The nsIAccessible associated with the event.
 May return null if no accessible is available

readonly attribute nsIAccessible accessible

 Accessible node geometrically above this one

nsIAccessible getAccessibleAbove()

 Accessible node geometrically below this one

nsIAccessible getAccessibleBelow()

 Accessible node related to this one 

nsIAccessible getAccessibleRelated(in unsigned long aRelationType)

 Accessible node geometrically to the left of this one

nsIAccessible getAccessibleToLeft()

 Accessible node geometrically to the right of this one

nsIAccessible getAccessibleToRight()

 Nth accessible child using zero-based index or last child if index less than zero

nsIAccessible getChildAt(in long aChildIndex)

 Accessible child which contains the coordinate at x,y

nsIAccessible getChildAtPoint(in long x, in long y)

 Returns the first accessible parent of a DOM node.
 Guaranteed not to return nsnull if the DOM node is in a document.
 @param aDOMNode The DOM node we need an accessible for.
 @return An first nsIAccessible found by crawling up the DOM node
         to the document root.

nsIAccessible getAccessibleInParentChain(in nsIDOMNode aDOMNode)

 Return an nsIAccessible for a DOM node in pres shell 0.
 Create a new accessible of the appropriate type if necessary,
 or use one from the accessibility cache if it already exists.
 @param aNode The DOM node to get an accessible for.
 @return The nsIAccessible for the given DOM node.

nsIAccessible getAccessibleFor(in nsIDOMNode aNode)

 Return an nsIAccessible for a DOM node in the given pres shell.
 Create a new accessible of the appropriate type if necessary,
 or use one from the accessibility cache if it already exists.
 @param aNode      The DOM node to get an accessible for.
 @param aPresShell The presentation shell which contains layout info for the DOM node.
 @return The nsIAccessible for the given DOM node.

nsIAccessible getAccessibleInShell(in nsIDOMNode aNode, in nsIPresShell aPresShell)

 Return an nsIAccessible for a DOM node in the given weak shell.
 Create a new accessible of the appropriate type if necessary,
 or use one from the accessibility cache if it already exists.
 @param aNode      The DOM node to get an accessible for.
 @param aPresShell The presentation shell which contains layout info for the DOM node.
 @return The nsIAccessible for the given DOM node.

nsIAccessible getAccessibleInWeakShell(in nsIDOMNode aNode, in nsIWeakReference aPresShell)

 Return an nsIAccessible for a DOM node in pres shell for this DOM window.
 Create a new accessible of the appropriate type if necessary,
 or use one from the accessibility cache if it already exists.
 @param aNode   The DOM node to get an accessible for.
 @param aDOMWin The DOM window containing the node.
 @return The nsIAccessible for the given DOM node.

nsIAccessible getAccessibleInWindow(in nsIDOMNode aNode, in nsIDOMWindow aDOMWin)

 Return an nsIAccessible for an already created DOM node in the given weak shell.
 Does not create a new one -- only returns cached accessibles.
 @param aNode      The DOM node to get an accessible for.
 @param aPresShell The presentation shell which contains layout info for the DOM node.
 @return The nsIAccessible for the given DOM node or null if
         an accessible does not already exist for this DOM node.

nsIAccessible getCachedAccessible(in nsIDOMNode aNode, in nsIWeakReference aShell)

 Returns a reference to the accessible object representing the specified
 selected child of the object.
 @param index Zero-based selected accessible child index 
 @return The nth selected accessible child

nsIAccessible refSelection(in long index)

 Get tree item from cache according to row and column, create if doesn't exist in cache
 "aColumn" can be nsnull

[noscript] nsIAccessible getCachedTreeitemAccessible(in PRInt32 aRow, in nsITreeColumn aColumn)