I always find MS Office is a good source for icon inspiration; how about the "pencil drawing a line" icon I've seen somewhere or other. Right-clicking a toolbar and selecting "customise" shows you them all.
I've seen Un*x and Windows software use the pencil for over 10 years. It's pretty common. IE also continues this convention, FWIW.
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Current PDA: Casio E-125. Past: Casio CQ-1 c. 1977. Seiko UC-3000, c. 1986. Casio B.O.S.S c. 1991.
We all live in a Yellow Submarine.