I'm using Texlipse to edit some LaTeX files, so it is very helpful to have the line wrap functionality. The one (the only one I found) I'm using now is Eclipse word-wrap plugin. However, the line numbers do not show correctly with this plugin.
How can I fix it?
Unfortunately the Word-Wrap plugin has this problem, as is stated at the bottom of the page you link to. There is no way around it.
This plug-in is only a quick hack to switch on the word wrap functionality of the text box widget that the Eclipse editors are build on top of, not a solid solution to the problem. Eclipse is not good with texts that need word wrap.