Find attached patch for making arrow keys usable on non-windows(Ubuntu in my case) platform. this patch will work in this way ---> key :- If item has no child , not effect.If it has children, and is not expanded. This key will expand it. If it has children and already expanded, go to first child.
<--- key :- If item has no child, go to parent item. If it has children and expanded , collapse it. If it has children and already collapsed, go to parent item.
Remaining two keys are working as they should be.
Patch looks good to me.
Commited with some coding style changes.
NOTE: Please do not change the copyrights for the sources at the moment, otherwise - we will be in inconsistent state for each source.