You want to customize the Ant editor's appearance.
Select Window Preferences Ant Editor, and choose from the items in that dialog.
You have some control over the Ant editor's appearance using the Window Preferences Ant Editor dialog. In Eclipse 2.1.2, the Ant editor is really little more than a simple XML editor, but you can specify such items as the colors used in syntax highlighting, and whether the editor shows an overview ruler or line numbers , as shown in Figure 7-13.
Figure 7-13. Setting options for the Ant editor
For example, turning on line numbers makes the Ant editor display them, as shown in Figure 7-14.