it is possible to customize the template of the tree base header (the column which contains the "+" and "-" icon when the grouping is active ) ?
I want to modify the content of the blank cells and display inside them a row number ({{row.grid.renderContainers.body.visibleRowsCache.indexOf(row)}}) ...
I found the content of the template I need to modify:
<i ng-class="
   { 'ui-grid-icon-minus-squared': 
       ( 
           (grid.options.showTreeExpandNoChildren && row.treeLevel > -1)
           || (row.treeNode.children && row.treeNode.children.length > 0)
       ) && row.treeNode.state === 'expanded', 
     'ui-grid-icon-plus-squared': 
       ( 
          (grid.options.showTreeExpandNoChildren && row.treeLevel > -1) 
          || ( row.treeNode.children && row.treeNode.children.length > 0)  
       ) 
     && row.treeNode.state === 'collapsed'
   }" 
   ng-style="{'padding-left': grid.options.treeIndent * row.treeLevel + 'px'}"
   class="ui-grid-icon-minus-squared" style="padding-left: 10px;">
</i>
...but I don't see how to change it and store my modification in the gridOption
 
     
    