From BlenderWiki

Size and position

Toggle in and out

(graphic way)

• Click on the small gray triangle top-left in the view to openup the Toolbar, or in the View menu choose "Toolbar"
• This opens a gray tab on the left of the view, where you can find Tools to use.
  The toolbar is modal, that is: it depends on the mode you selected in the view
• Click again to toggle in and out the view

(shortcut)

Alternatively, press T

Resize

Click and drag the triangle to resize the toolbar

You can also get the toolbar in and out by dragging the triangle:

• If the toolbar is hidden, drag it in the view.
• If the toolbar is in the view, drag it away from the view.

(to be written)