Add background color in QSettings

[NicolasRannou]

So when we reopen gofigure, the good background color is displayed.

[arnaudgelas]

Background color are tab dependent, so if you have 1 yellow and 1 black.
Next time you open it, the color used will depend on the order you close the tab...

Unless a more elaborate mechanism is in place (based on the name of the image / imaging session ), this issue won't be solved...

[NicolasRannou]

I guess it's fine, the same user will not set up different colors in general?
Moreover default color shouldn't be black, for i.e., dark grey look much better.

[arnaudgelas]

You never know (depends on the background of your image, which may not necessary be black).
Thus, you should be able to set different colors based on the image / imaging session you are looking at.

About dark grey: this is your personal preference which may not be the case for everyone, for every kind of images.

[NicolasRannou]

ok
for the default color, I would say it shouldn't be black assuming the "background" of an image is black already..?

[arnaudgelas]

yep