GFx uses list boxes for input of everything except text and button pushes. List boxes are used for selection from a list of items. These items may be simply the choices yes or no, an integer choice or list of other items such as colors. The Plot input window has several list boxes for many different choices. List boxes are distiguished from Text boxes by the up and/or down arrows at the right of the List box.
Take for example the color list box for the either the data segment (curve) or Text. Initially this box looks like:
If the downward pointing arrow at the right of the list box is clicked on the list choice changes and the upward arrow appears indicating that there is also a choice in that direction now. Several down clicks get you to the following position:
Continuing to click the down arrow untill you reach the bottom of the list gets you to this position:
At this point the down arrow disappears and only the up arrow remains, indicating that choices are only available in that direction. If the list box only has two choices the case with both arrows visible will not occur.