chore(demo): example with Tree Formatter

Author: ghiscoding

src/app/examples/grid-tree-data-hierarchical.component.scss

@@ -10,6 +10,9 @@
 .total-suffix {
   margin-left: 10px;
 }
+.hidden {
+  display: none;
+}
 
 /*
   www.OnlineWebFonts.Com

src/app/examples/grid-tree-data-hierarchical.component.ts

@@ -270,12 +270,12 @@ export class GridTreeDataHierarchicalComponent implements OnInit {
     if (data[idx + 1]?.[treeLevelPropName] > data[idx][treeLevelPropName] || data[idx]['__hasChildren']) {
       const folderPrefix = `<span class="mdi icon color-alt-warning ${dataContext.__collapsed ? 'mdi-folder' : 'mdi-folder-open'}"></span>`;
       if (dataContext.__collapsed) {
-        return `${exportIndentationLeadingChar}${spacer}${indentSpacer} <span class="slick-group-toggle collapsed" level="${treeLevel}"></span>${folderPrefix} ${prefix} ${value}`;
+        return `<span class="hidden">${exportIndentationLeadingChar}</span>${spacer}${indentSpacer} <span class="slick-group-toggle collapsed" level="${treeLevel}"></span>${folderPrefix} ${prefix} ${value}`;
       } else {
-        return `${exportIndentationLeadingChar}${spacer}${indentSpacer} <span class="slick-group-toggle expanded" level="${treeLevel}"></span>${folderPrefix} ${prefix} ${value}`;
+        return `<span class="hidden">${exportIndentationLeadingChar}</span>${spacer}${indentSpacer} <span class="slick-group-toggle expanded" level="${treeLevel}"></span>${folderPrefix} ${prefix} ${value}`;
       }
     } else {
-      return `${exportIndentationLeadingChar}${spacer}${indentSpacer} <span class="slick-group-toggle" level="${treeLevel}"></span>${prefix} ${value}`;
+      return `<span class="hidden">${exportIndentationLeadingChar}</span>${spacer}${indentSpacer} <span class="slick-group-toggle" level="${treeLevel}"></span>${prefix} ${value}`;
     }
   };