static/ext/src/ux/AceEditor.js
function(assignment) {
        // This is all about re-creating Assignments
        if (assignment.param.name !== '__command') {
            return;
        }

        this._assignments = {};

        if (assignment.value) {
            assignment.value.params.forEach(function(param) {
                this._assignments[param.name] = new Assignment(param, this);
            }, this);
        }

        this.assignmentCount = Object.keys(this._assignments).length;
        this._dispatchEvent('commandChange', { command: assignment.value });
    }
function(assignment) {
        // This is all about re-creating Assignments
        if (assignment.param.name !== '__command') {
            return;
        }

        this._assignments = {};

        if (assignment.value) {
            assignment.value.params.forEach(function(param) {
                this._assignments[param.name] = new Assignment(param, this);
            }, this);
        }

        this.assignmentCount = Object.keys(this._assignments).length;
        this._dispatchEvent('commandChange', { command: assignment.value });
    }
When the command changes, we need to keep a bunch of stuff in sync