When on and a selection is active, fills stay inside the selection.

When on, fill stops at edges and only spreads through touching pixels of the same color. When off, every matching pixel on the layer is filled (including separate areas).

Higher tolerance fills pixels with similar colors (useful for anti-aliased edges). 0 requires an exact color match.

Bleeds the filled region outward by this many pixels after the flood fill (0 = no bleed). Selection/layer limits are also expanded by the same amount when a selection is active.

When on, the fill follows visible color (all layers with visibility on and opacity above 0) but only paints empty pixels on the active layer. Lines or shapes that change the visible color stop the flood; same-color pixels on other layers do not.