Double Clicking Folder Tree does not open up child nodes ...

Double Clicking Folder Tree does not open up child nodes ...

In the left navigation menu, double clicking a folder tree should actually open up the child nodes. But it does not. I  have to necessarily click the +/- sign to do that. Windows Explorer does it through double click.

Can we fix this?

----
Deepak Vasudevan
http://thamizhththendral.blogspot.com/