The DOM explorer is populated only when a test is in record mode.
The DOM Explorer allows you to inspect all elements of the tested application at once, shown in a tree-like or in a grouped-by-tag view. The DOM Explorer is helpful with a complex applications where simply taping may not be enough to find the element you're looking for. It is used also for building steps through the Step Builder
In order to access it click DOM Explorer tab in the middle bottom pane.
The DOM Explorer Toolbar provides some additional features that may come handy.
Highlight the element - toggle this button whether to highlight the element in the tested application or not. When it is enabled the selected element from the DOM tree will be surrounded by a red rectangle on the recording device. This feature works only for Native apps.
Search for element - to search an element in the DOM. The found element will be selected automatically.
Elements Tree View - displays elements in their original tree-like hierarchy order.
Elements Tag View - displays elements grouped by their tagname.
View Selector - displayed only when Hybrid test is in record mode. Use it to select the Native/Web view which DOM tree you need loaded.