Color gestures
A new method for quick and precise adjustment of colors is added in this version: color gestures. It works on the selected objects by grabbing the fill or stroke color swatch in the selected style indicator (on the left of the statusbar) and dragging it in various directions as described below. Note that this only works when the swatch displays a flat color; it does not work for a swatch showing "None", "N/A", or displaying a gradient (although you can select one or more gradient stops in Gradient tool and color-adjust them by color gestures just as you would do for objects). Color gestures can work on fill or stroke, depending on which swatch in the selected color indicator you drag.
Color gestures work in HSL color space. Dragging without any keyboard modifiers adjusts the hue channel, dragging with Shift adjusts saturation, and dragging with Ctrl adjusts lightness.
The adjustment is done by rotating the color swatch away from the original direction which is assumed to be NE at 45 degrees (i.e. from the swatch into the document window). That is, once you click and drag the color swatch, imagine a line going from the point where you clicked in the NE direction, across the entire Inkscape window. By dragging below or to the right of that line, you decrease the corresponding color channel, to the minimum at the lower edge of the window; by dragging it above or to the left, you increase it, to the maximum at the left edge of the window. If you hover your mouse exactly over the 45 degrees line, the change will be zero.
Note that you can easily vary the precision of your adjustment. If you drag close enough to the swatch, each small movement results in a big change of the color. If you need a finer adjustment, just drag farther away from the swatch, towards the center of the Inkscape window or even to its upper right corner, where minute movements will produce very small changes in the color. In fact, this method gives you more color precision than even the color wheel in the Fill and Stroke dialog, unless you expand that dialog to fill the entire screen which is rarely practical.
Watch the statusbar which will indicate, as you drag, the channel you are adjusting, the original value of that channel, and the new value.
You can switch channels while you drag. That is, you don't need to restart dragging from the swatch if you want to adjust all three channels - you can do it in one drag, pressing and releasing Ctrl and Shift as necessary. Note that when you change the keyboard modifiers during drag, the position of the zero-change line is temporarily set to the current position of the mouse; this is done so that there are no sudden changes in color if you are switching modifiers away from the original 45-degree line.
For example, you can select a green rectangle and first turn it into greenish-blue by dragging away from the Fill swatch and slightly above the 45 degrees line; then, without releasing the mouse, press Ctrl and drag a bit to the right to darken the color; then press Shift, release Ctrl, and adjust saturation. You can press or release Ctrl and Shift as many times as necessary during a single drag; when you are finally satisfied with your color, release the mouse to commit the change.
Apart from precise adjustments, you can use color gestures to quickly perform common color transformations:
* Ctrl+drag the swatch to the right and down to color all selected objects black.
* Ctrl+drag the swatch upwards and to the left to color all selected objects white.
* Shift+drag the swatch to the right and down to desaturate the color of selected objects.
* Shift+drag the swatch upwards and to the left to maximize saturation of the color of selected objects.
Note that when several objects or gradient stops with different colors are selected, the selected style indicator shows their averaged color. If you adjust that color by gesturing, the changed color will be assigned back to all selected objects/stops, in effect eliminating any difference between them. If you want to adjust many different-colored objects preserving their relative differences, use the color modes of the Tweak tool or color adjustment extension effects.
This new technique requires some getting used to, but once you get the idea it is quite convenient, fast, and precise.