[Fixed Position] Improve button support

Improve button support from toolbars by adding a click
function when generating structures for mct-toolbar based
on view definitions. WTD-879.

platform/commonUI/edit/README.md

@@ -15,6 +15,8 @@ view's scope.) These additional properties are:
   then that function is assumed to be an accessor-mutator function
   (that is, it will be called with no arguments to get, and with
   an argument to set.)
+* `method`: Name of a method to invoke upon a selected object when
+  a control is activated, e.g. on a button click.
 * `inclusive`: Optional; true if this control should be considered
   applicable whenever at least one element in the selection has
   the associated property. Otherwise, all members of the current

platform/commonUI/edit/src/representers/EditToolbar.js

@@ -106,23 +106,41 @@ define(
             // to the current selection.
             function isApplicable(item) {
                 var property = (item || {}).property,
+                    method = (item || {}).method,
                     exclusive = !(item || {}).inclusive;
 
                 // Check if a selected item defines this property
                 function hasProperty(selected) {
-                    return selected[property] !== undefined;
+                    return (property && (selected[property] !== undefined)) ||
+                            (method && (typeof selected[method] === 'function'));
                 }
 
-                return property && selection.map(hasProperty).reduce(
+                return selection.map(hasProperty).reduce(
                     exclusive ? and : or,
                     exclusive
                 ) && isConsistent(property);
             }
 
+            // Invoke all functions in selections with the given name
+            function invoke(method, value) {
+                if (method) {
+                    selection.forEach(function (selected) {
+                        if (typeof selected[method] === 'function') {
+                            selected[method](value);
+                        }
+                    });
+                }
+            }
+
             // Prepare a toolbar item based on current selection
             function convertItem(item) {
                 var converted = Object.create(item || {});
-                converted.key = addKey(item.property);
+                if (item.property) {
+                    converted.key = addKey(item.property);
+                }
+                if (item.method) {
+                    converted.click = function (v) { invoke(item.method, v); };
+                }
                 return converted;
             }