Coupling of the Views
The really strong point of WinDirStat is, that the three views, Directory List, Extension List and Treemap, are coupled with each other.
Directory List -> Treemap
When you select an item (directory or file) in the directory list, the treemap also shows this item by highlighting it with a colored frame. In particular you can see the size of directories.
Treemap -> Directory List
When you click into the treemap, the mouse always hits a file (a colored rectangle). After that the directory list expands (if necessary) the appropriate nodes and selects this file. So you can, e.g. by clicking on a big rectangle, see path and attributes of the corresponding big file in the directory list.
So, because of this mutual coupling, the selections in the directory list and in the treemap are always the same.
Directory List + Treemap -> Extension List
When you select a file in the directory list (or in the treemap), the extension list shows the file type (the extension). The extension is selected and scrolled into view. So you can see the description and the statistics for this file type.
Extension List -> Treemap
When you select a file type in the extension list, the treemap highlights all files of this type.