GIMP has tools that fill an entire layer, selection, or image. The only options they share with other painting tools are MODE and OPACITY.
The Bucket Fill tool () can fill a layer, a selection, or all pixels of a similar color in the layer or selection. Its icon and pointer are shown in Figure 15-18, and its options are shown in Figure 15-19. To use it, click once in the area that you want to fill.
Here are the options specific to this tool:
FILL TYPE determines whether the area is filled with the foreground color, background color, or a pattern. The key toggles between the foreground and background colors. ...