Re: Screen Size on iBook G3
I have a similar problem because I can't have a 1440x900 resolution, which I should have. If I choose it (I can, using xrandr or any gui settings), I have a problem like yours, just the upper left part of the screen used and clippng part of the desktop (like if it was hiding to the outside of the screen).
I found no solution, I keep the 1280x800 resolution, which is not bad, but still...
Anyway, did you simply try to change the resolution (with xrandr changing the modes or from the screen settings?)
Linux Mint 17.3 running on my AMD A8-6600K desktop; .Ubuntu 15.10 running on a Intel i5 6200U @2.30 GHz laptop