In Eclipse Helios I want to highlight selected lines using a custom background color, like one would do with a text marker for normal text on paper.
How can I do tha
If you want to make your own marker type and dictate what the text annotation should look like, read through http://www.eclipse.org/articles/Article-Mark%20My%20Words/mark-my-words.html . If you're looking to do this with your own file type, you'll have to go into more detail--and pick a file type that can support remembering such things itself.