You can multi-select tasks on the WBS using CRTL+right click (or CMD on Mac) and move or structure by dropping on one of the tasks.
Alternatively you can move the tasks using the arrows found on the header and a notification will be displayed if the operation was partially successful or unsuccessful.
|Selecting more than one task is possible with (selected tasks are highlighted in blue):|
|cmd or ctrl + left mouse button||select tasks one by one|
|shift + left mouse button||select a range of tasks|
|Unselecting tasks is possible with:|
|ESC||unselect all selected tasks|
|click out of zone||unselect all selected tasks|
|cmd or ctrl + left mouse button||unselecting tasks one by one|
a) parent + all his children: move up/down, indent, outdent, delete
b) parent + not all children/without children: delete
c) all children from one parent, but without a parent: outdent, delete
d) not all children from one parent, but without a parent: move up/down, indent, outdent, delete
e) a lot of children from different parents, but without parents: delete
f) a lot of parents without children: delete
To learn more about structuring go to Scope module - Building WBS (task hierarchy).