Fix scale to content when colors are inverted

[vmhl87]

Resizing with 'W' fits to content by looking for white squares in the margins. This doesn't work with inverted colors, as the background is black.

A small change to lmargin() and rmargin() fixes this behavior.

[aligrudi]

Vincent Loh ***@***.***> wrote:

Resizing with 'W' fits to content by looking for white squares in the margins. This doesn't work with inverted colors, as the background is black. A small change to lmargin() and rmargin() fixes this behavior. You can view, comment on, or merge this pull request online at: #14

Sorry for the long delay. I was planning to fix this after removing fbval_t type. Thanks for the patch. Ali

[vmhl87]

Thank you so much! No problem.