WoW:FrameXML elements
Overview
This document describes various important UI elements which are provided by the standard World of Warcraft FrameXML UI.
Tooltips
GameTooltip
This is the game's tooltip, it consists of a number of lines, to determine how many there are, you can call the GameTooltip:NumLines() function.
GameTooltipTextLeft<num>
Each line of text from the game tooltip is represented by one of these objects, replace <num> with the appropriate line number. To obtain the text of a line call the GameTooltipTextLeft<i><num></i>:GetText() function.
Not sure if there is a way to dynamically form a function name in lua based on a variable (which would allow easily looping through all tooltip lines).