sunburst & treemap root color attribute

src/traces/sunburst/attributes.js

@@ -215,5 +215,18 @@ module.exports = {
     },
     sort: pieAttrs.sort,
 
+    root: {
+        color: {
+            valType: 'color',
+            editType: 'style',
+            role: 'style',
+            dflt: 'rgba(0,0,0,0)',
+            description: [
+                'sets the color of the root node for a sunburst or a treemap trace.'
+            ].join(' ')
+        },
+        editType: 'calc'
+    },
+
     domain: domainAttrs({name: 'sunburst', trace: true, editType: 'calc'})
 };

src/traces/sunburst/calc.js

@@ -276,8 +276,8 @@ exports._runCrossTraceCalc = function(desiredType, gd) {
                     dfltColorCount++;
                 }
             } else {
-                // root gets no coloring by default
-                cdi.color = 'rgba(0,0,0,0)';
+                // set root color. no coloring by default.
+                cdi.color = cdi.trace.root.color;
             }
         }
     }

src/traces/sunburst/defaults.js

@@ -77,6 +77,8 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
 
     coerce('rotation');
 
+    coerce('root.color');
+
     handleDomainDefaults(traceOut, layout, coerce);
 
     // do not support transforms for now

src/traces/treemap/attributes.js

@@ -269,6 +269,7 @@ module.exports = {
         ].join(' ')
     },
     sort: pieAttrs.sort,
+    root: sunburstAttrs.root,
 
     domain: domainAttrs({name: 'treemap', trace: true, editType: 'calc'}),
 };

src/traces/treemap/defaults.js

@@ -116,6 +116,8 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
 
     coerce('sort');
 
+    coerce('root.color');
+
     handleDomainDefaults(traceOut, layout, coerce);
 
     // do not support transforms for now