Using Masks and Layers—Painting, Filling, and Color Tools - GIMP 2.6 for Photographers: Image Editing with Open Source Software - page 224

All other text attributes, such as font, size, and color, are defined in the
Tool Options dialog. You can set these attributes in advance and change them
whenever you wish. To change existing text, select the text layer in the Layers
dialog. Select the Text tool and click it on the text in the image. The Text Editor
dialog opens to display the text, which you can now edit along with the
following Tool Options attributes:
• Font : Clicking the button next to Font opens a drop-down list of all fonts
installed on your computer, along with a small sample of each.
• Size : You can set the size of the font in the currently selected unit of
measurement. The drop-down menu beside it allows you to choose a
unit: px (pixel), in (inch), mm (millimeter), pt (point), pc (pica), and More .
Note that 1 point (pt) = 1/72 inch = 2.54 cm/72, and 1 pica = 12 points,
which is the standard font size.
• Hinting/Force auto-hinter : Hinting or auto-hinting is a unique function
of GIMP that optimizes the representation of text in an image while
(automatically) correcting representation errors. Whereas hinting uses
representation information embedded in the text font, auto-hinting tries
to compute the corresponding information itself.
• Antialiasing : Renders text with much smoother edges and curves. By inserting
semi-opaque pixels, blending toward transparency at the edges of the text, the
anti-aliasing option radically improves the appearance of rendered typeface
by smoothing the edges. (See also section 1.3.1 and figure 1.3).
• Color : By default, GIMP uses the color set as Foreground Color in the color
area as the color for text. With the Text tool options dialog, you can set
or change a text color before, during, or after typing text. Just click the
colored button and a familiar color editor dialog will appear.
• Justify : If your text is more than one line in length, you can justify it
according to the options available in the editor: left-justified, , right-justified, ,
centered , or illed (justified). Additionally, you can choose whether the
text will read from left to right or from right to left . This is particularly useful
when switching from Western languages to Middle Eastern languages
because the latter is read from right to left.
• Indent : You can modify the values to indent the lines respective to a
block of text from the left margin. Negative values can be used as well.
• Line Spacing : This option controls the spacing between successive lines
of text. You can reduce or increase the value.
• Letter Spacing : This option controls the spacing between letters in a row.
You can reduce the spacing by negative values or increase it by values
greater than zero. This way you can produce spaced text.
• Text along Path : If you apply a path to a curve or a circle in an image,
you can also align text on this path by using this feature. (Paths will be
discussed in section 3.11.)
• Path from Text : This button will convert your text into a vector or path.
Paths are used to efficiently create selections according to a figure's
contour.

Figure 3.48
The Text tool options dialog