4. The system of claim 1 , wherein the highlight rendering service interface includes an add-segment method to enable the extension to create a highlighted segment between two display pointers in the document.
4. The system of claim 1 , wherein the highlight rendering service interface includes an add-segment method to enable the extension to create a highlighted segment between two display pointers in the document. 5. The system of claim 4 , wherein the highlight rendering service interface is for defining a style of the highlighted segment.