restore "x" in messageBox(), add namespace#tag to $element()

dom.js

@@ -81,11 +81,16 @@ function $$(selector, base = document) {
 
 
 function $element(opt) {
-  // tag:              string, default 'div'
+  // tag:              string, default 'div', may include namespace like 'ns#tag'
   // appendChild:      element or an array of elements
   // dataset:          object
   // any DOM property: assigned as is
-  const element = document.createElement(opt.tag || 'div');
+  const [ns, tag] = opt.tag && opt.tag.includes('#')
+    ? opt.tag.split('#')
+    : [null, opt.tag];
+  const element = ns
+    ? document.createElementNS(ns == 'SVG' || ns == 'svg' ? 'http://www.w3.org/2000/svg' : ns, tag)
+    : document.createElement(tag || 'div');
   (opt.appendChild instanceof Array ? opt.appendChild : [opt.appendChild])
     .forEach(child => child && element.appendChild(child));
   delete opt.appendChild;
@@ -94,5 +99,12 @@ function $element(opt) {
     Object.assign(element.dataset, opt.dataset);
     delete opt.dataset;
   }
-  return Object.assign(element, opt);
+  if (ns) {
+    for (const attr in opt) {
+      element.setAttributeNS(null, attr, opt[attr]);
+    }
+  } else {
+    Object.assign(element, opt);
+  }
+  return element;
 }

msgbox/msgbox.js

@@ -56,9 +56,12 @@ function messageBox({
     messageBox.element = $element({id, className, appendChild: [
       $element({appendChild: [
         $element({id: `${id}-title`, innerHTML: title}),
-        $element({
-          id: `${id}-close-icon`,
-          innerHTML: '<svg class="svg-icon"><use xlink:href="#svg-icon-close"/></svg>',
+        $element({id: `${id}-close-icon`, appendChild:
+          $element({tag: 'SVG#svg', class: 'svg-icon', viewBox: '0 0 20 20', appendChild:
+            $element({tag: 'SVG#path', d: 'M11.69,10l4.55,4.55-1.69,1.69L10,11.69,' +
+              '5.45,16.23,3.77,14.55,8.31,10,3.77,5.45,5.45,3.77,10,8.31l4.55-4.55,1.69,1.69Z',
+            })
+          }),
           onclick: messageBox.listeners.closeIcon}),
         $element({id: `${id}-contents`, [putAs]: contents}),
         $element({id: `${id}-buttons`, appendChild: