[patch] implement letter key navigation in Tree

[Becky Gibson]

A user should be able to move focus from open node to open node in a tree by pressing the first letter of the node name. This allows for fast keyboard navigation through the tree items. With no additional keys pressed the first node beginning with the letter will be focused and selected. When more than one entry exists that begins with the same letter, pressing the letter key again will find the next entry. Letter key navigation should also work with multi-selection. If you press and hold the ctrl-key with a letter key, the found node will be focused, press space to add the focused node to the selection.

[Becky Gibson]

The dijit version of the tree does not support multi-selection so that portion of the above description can be ignored. For code samples see:

​http://www.weba11y.com/AjaxDemo/sample.html ​http://www.mozilla.org/access/dhtml/class/tree

[ptbrunet]

No need to support multi-selections.

[guest]

Working key navigation

[guest]

I have added an attachment with working key navigation. obi068 at kabsi.at

Tested with IE7 only! There are some other problems with the focus at startup!

[bill]

Not sure who obi068 at kabsi.at is; have you filed a CLA?

[guest]

obi068: i have sent it today!

[alex]

we should probably land this for 0.9 final. Moving out to that milestone.

[Becky Gibson]

(In [9809]) fixes #2193 changes by obi068 and ptbrunet (CLAs on file) to implement letter key navigation in tree