Ensure color mixer works in New dialog

and sync README docs to capture that it, and rainbow palette,
may be used.

docs/fr_FR.UTF-8/html/README.html

@@ -29,7 +29,7 @@
       </p>
 
       <p>
-        février 21, 2022      </p>
+        février 23, 2022      </p>
     </center>
 
     <hr size="2"
@@ -351,7 +351,7 @@
                  "[Couleurs - Noir, Blanc, Rouge, Rose, Orange, Jaune, Vert, Cyan, Bleu, Pourpre, Brun, Gris]">
             </p>
 
-            <p>
+            <p id="special_color_options">
               On the far right are three special color options:              <ul>
                 <li>The "color picker" (which has an outline of an eye-dropper) allows you to pick a color found within your drawing. A shortcut key is available to access this feature quickly; see below.                <li>The rainbow palette allows you to pick a color from within a box containing thousands of colors.</li>
                 <li>The "color mixer" (which has silhouette of a paint palette) allows you to create colors by blending primary additive colors &mdash; red, yellow, and blue &mdash; along with white (to "tint"), grey (to "tone"), and black (to "shade").  The ratios of colors added are shown at the bottom.</li>
@@ -867,6 +867,13 @@
 
               <p>
                 <strong>Remarque :</strong> vous pouvez également appuyer <b><code>[Control / &#8984;]</code></b> + <code><b>[N]</b></code> sur le clavier pour commencer un nouveau dessin.              </p>
+
+              <strong>Special Solid Background Color Choices</strong>
+              <blockquote>
+                <p>
+                  Along with the preset solid colors, you can also choose colors using a rainbow palette or a "color mixer". These operate identically to the options found in the color palette shown below the canvas when drawing a picture. See <a href="#special_color_options">Main Screen &gt; Lower: Colors &gt; Special color options</a> for details.                </p>
+              </blockquote>
+
               <strong>Images de "Démarrage" et images "Modèle"</strong>
               <blockquote>
                 <p>