With the Fill tool K, click inside an area to flood it with the primary colour. The fill spreads through connected pixels of the clicked colour and respects any active selection.
| Modifier | Fill |
|---|---|
| none | Flood-fill the connected area. |
| Control | Non-contiguous: recolour every matching pixel on the layer, connected or not. |
| Command | Outline: paint only the border of the area. |
| Command+Control | Outline including diagonal corners, for a fully closed border. |
Fills use the current dither level, so a 50% dither fills with a checkerboard of primary and secondary.
To fill an area with a dithered gradient from the primary to the secondary colour:
Select the Fill tool.
Hold Shift and drag across the area. The drag direction and length set the gradient axis, and the fill previews live as you drag.
Release to commit.
The gradient ramps through Bayer dither patterns—pure primary at the start of the drag, pure secondary at the end. A Shift-click without dragging fills solid.