Flood fill - option to only take pixel layers within a group/ layer into account

[Intuos5]

Usually, I work with multiple layers: one is a trace-over background and then I have a group with design layers (line-work, fills and some other miscellaneous pixel layers). Something like this:

I would like to have a 4th option in the Flood fill tool, which is: below, only within current layer/ group.

This ensures that my trace-over layer will be discarded when filling, because it is outside of the design layer that I work in.