Of the four new modes, two are for editing path shapes (Attract and Repel) and two are for coloring objects (Color Paint and Color Jitter) . I also renamed Melt to Shrink and Inflate to Grow as discussed before.
* The Attract and Repel modes work by moving each affected point on a path towards (Attract) or from (Repel) the cursor point. In some cases this may look similar to Shrink and Grow, but the difference is that shrinking/growing moves paths perpendicularly to the path in each point, whereas attracting/repelling moves them to or from the cursor regardless of the path shape. These modes are similar to the Pinch effect in ; you can use them for various central-symmetric distortions in parts of your paths.
Color-changing modes
The Color Paint and Color Jitter modes, unlike the path editing modes, change the colors of objects instead of their shapes. Yet they share enough common features with the path-changing modes to be part of the same tool: These modes also use a circular soft-edged brush controlled by the Width and Force parameters on the Controls bar and affected by the pen pressure (if you have a pressure-sensitive tablet).
* Color Paint applies the style of the tool to the selected objects under the brush. The style of the tool is visible in the style swatch at the rightmost end of the tool's control bar; it can be changed by clicking on the color palette or by any other style assignment command, such as Fill and Stroke dialog. (Note: unlike all other tools, in Tweak tool in Color Paint mode you cannot assign style directly to selected objects; any style-setting command changes the tool's style instead.)
The fill from the tool's style applies to the fills of the painted objects, and the stroke applies to the strokes. If the tool's style has no fill or no stroke, it won't affect fills or strokes, correspondingly. For example, if you want to color the fills of objects blue but leave their strokes untouched, assign blue fill to the tool's style (just click blue on the palette) but set its stroke to None (middle-click the Stroke swatch in the statusbar). Similarly, master opacity in the tool's style
This mode allows you to literally paint over objects, shifting their colors towards the target style of the tool. For example, if you paint with yellow fill over a blue-filled object, the object will become greenish blue, then green, then yellowish green, and end up being exactly the green color you're painting with. This speed of this gradual transition depends on the Force and pen pressure; also, objects touched by the periphery of the brush are less affected than those hit by the brush center. Overall, using this tool is very similar to a soft brush in a raster editor such as Gimp or Photoshop.
* Color Jitter mode does not apply any color, but instead jitters (randomizes) the colors of the objects it touches. The force of the action determines how strong is the randomization, i.e. how far the colors deviate from the original values. This mode does not use the tool's style.
Both modes work on flat fills and gradients; for gradients, the tool takes into account not only the position of the entire object with gradient, but also the position of each gradient stop relative to the brush. This means that, for example, you can change the blue color only in an object filled with blue-red gradient simply by painting over its blue end with a brush small enough to not touch the red.
Channels
Color Paint and Color Jitter honor the Channels control. This control comprises the four buttons: H, S, L, and O, which allow you to turn on and off the tool's action on the object's hue, saturation, lightness, and opacity, correspondingly. For example, if you want to raise the saturation of some part of your drawing without changing the hue, select some maximum-saturation color (e.g. pure red) and turn off all Channels buttons except S. Similarly, you can replace the hues without affecting saturation or lightness (only H pressed), or lighten/darken all colors without changing their hues and saturation (only L pressed). Pressing O allows you to apply the master opacity from the tool's style to the master opacity of objects (but not fill or stroke opacity).
Usage notes
Color painting with Tweak tool is similar, but not exactly analogous to bitmap painting. Even though the tool itself works as a soft brush, it still applies its color to vector objects, which behave as vector objects usually do. For example, if you want to change the tint of the face in your drawing, and if a hand in the drawing is part of the same object as the face, that hand will change its tint too even if it's located far from the point you are painting. (We foresee a "fracture" command in one of the next versions of Inkscape which will help you turn a monolithic object into a mosaic of small fragments that will be then easy to paint with Tweak tool.) Still, even with this limitation, color painting is a novel way of dealing with vector drawings which allows you to quickly and intuitively make adjustments which would be awkward and slow with traditional approach.
Drawings containing patterns or scatterings of small independent objects are best suited for color painting with Tweak tool. Examples include:
* freehand drawings with Calligraphy pen, consisting of many separate strokes;
* gradient meshes imported from Adobe Illustrator files (Inkscape renders these meshes as lattices of small polygons; while there's no direct support for gradient meshes in Inkscape yet, color painting on such lattices is almost as good);
* text converted to paths and with Break Apart command applied so that each letter is a separate path;
* patterns made with the Tile Clones command; note that you need to unset the fill and/or stroke on the original object and use the Color tab to assign some initial color to the clones - this will make them paintable with the Tweak tool without unlinking.
Moreover, color tweaking can be useful for compositions with a few objects or even for single objects. Unlike all other color selection methods, painting with the Tweak tool implements the color mixing metaphor which is much more familiar to traditional artists than RGB sliders or even the color wheel. For example, start with a rectagle of pure blue color; then, pick different colors by Color Paint and apply light touches with minimum Force and minimum pen pressure: add a little green, a little brown, a little yellow, etc. until you have the exact hue you need. Similarly, you can whiten or blacken any hue by admixing white or black.
You can also use color tweaking to add a tint, darken/lighten, saturate/desaturate, or color jitter your entire drawing. Just select all in all layers, zoom out, choose a large brush width so it covers all of the drawing, and apply a little color tweaking (with minimum Force) that will therefore affect all visible objects.