API GameTooltip ClearLines

Clear the lines of a tooltip, both left and right. GameTooltip:ClearLines;

Details

 * If this method is called when the GameTooltip is visible it will clear all the text but won't hide it
 * The text isn't actually cleared, merely hidden. After a call to this method, the text can still be retrieved using FontString:GetText on the GameTooltip's FontString children.
 * The owner of the GameTooltip is cleared. i.e. calling GameTooltip:GetOwner after calling this method will return nil.