The PICKAUTO system variable has been updated in AutoCAD 2012 to provide more flexibility when selecting objects. If you’re not familiar with the details of PICKAUTO, let me explain.
The PICKAUTO system variable controls automatic window selection. When it’s set to 0, automatic window selection is disabled requiring you to actually pick on objects to select them. The only way to create a window or crossing selection is to specify one of those options at the command line (W or C). When PICKAUTO is set to 1, AutoCAD still selects the object when you click directly on it but if you click in a blank part of the drawing, it implies a window or crossing selection (depending which way you drag the cursor). That’s good… but AutoCAD 2012 is even better with an additional PICKAUTO option.
When PICKAUTO is set to 2, AutoCAD still selects the object if you click and release on the object. And, it still implies a window or crossing selection if you click and drag on a blank part of the drawing. But it also allows you to click on an object and, while keeping the mouse button pressed, drag to imply a window or crossing selection.