How Do I Enable Bookmarks in Eclipse?

I am using Eclipse (Version: Helios Service Release 2 Build id: 20110301-1815) for a PHP project and would like to use the Bookmark fea开发者_JAVA百科ture. However, right-clicking in the margin shows the Add Bookmark item dimmed out. The Edit menu also shows it dimmed out. For that matter, Add Task is also dimmed out in both locations.

How do I turn on this feature?

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Make sure you're in a project and that the file you want to place a bookmark in belongs to that project. Otherwise it won't work.