In the same way that menus can be moved around, as was explained Section 4.2.1 ― The Menubar, toolbars can be moved around the Gnumeric window by dragging the little tag on the leftmost portion of the toolbar.
If the Gnumeric window is too small to fit all of the toolbar buttons, gnumeric may display a little right pointing black arrow to indicate that there are more options. If the user clicks on this arrow, a window will open with the remaining buttons.
Certain toolbar options, such as the zoom box, are combinations of a button or text entry area and a downward pointing arrow. If the user clicks on the arrow, a list of available options appears.