This tool is selected by default in the field selection toolbox. Click boxes in the work area to select them. This tool is selected by default in the field selection toolbox. Click boxes in the work area to select them.
Click and drag the arrow over an area on the screen using the primary mouse button to select all boxes within the area dragged.
Click individual boxes while pressing the ALT or CTL keys on the keyboard.
Click the Select all objects button 
in the upper toolbar to select all boxes in the work area.