Code review comment for lp://qastaging/~fboudra/linaro-image-tools/highlight

Salgado made a couple of suggestions in
https://code.launchpad.net/~zkrynicki/linaro-image-tools/hacking/+merge/49615,
which I think should be considered.

As for the width of the Selected column, it could either be made
wider, or perhaps leave it without a heading and just have like a 4
char arrow.

Thanks,

Mattias