Middle Mouse Button on an Object in the Outliner should select all children

It's very frustrating to select all children in deep hierarchies.

"Select Hierarchy" only works on a single object and is much slower than clicking. It's not possible to Ctrl+"Select Hierarchy" to add a hierarchy to the selection. MMB is currently used to pan the Outliner, this is not very useful.

Instead, MMB on an object should select the object and all its children. Ctrl+MMB should add the object and its children to the selection.