Hierarchical display of Articles in CMS

Beta Valve have a number of article categories. 
In the CMS editor when you view articles, it shows them on the left hand side in a date order. Beta Valve would like it to have a sort of hierarchical display, where the Article Category is the 'Parent' and the articles underneath it is the 'children'.  This means they would be able to select a specific category and edit articles in it, rather than searching through using date order.