Before extending the selection:
| "\n    "
| <p>
|   "The quick brown fox jumped over the "
|   <span>
|     id="start"
|     "<#selection-anchor>lazy dog.<#selection-focus>"
| "\n    "
| <p>
|   <span>
|     id="end"
|     "T"
|   "he quick brown fox jumped over the lazy dog."
| "\n"

After extending the selection:
| "\n    "
| <p>
|   "The quick brown fox jumped over the "
|   <span>
|     id="start"
|     "<#selection-anchor>lazy dog."
| "\n    "
| <p>
|   <span>
|     id="end"
|     "T<#selection-focus>"
|   "he quick brown fox jumped over the lazy dog."
| "\n"