Appends an ellipsis to this text block
public void AddEllipsis();
This method checks if the text block has already been truncated and if not appends an ellipsis without changing the measured vertical layout of the text block. The ellipsis only remains in effect until the block's layout is recalculated.
The text block must have at least one line. If the block contains no text, then use AddText("\n", style) to create a single line with an attached style but no text.
The intended purpose of this is to included an ellipsis on this text block when a following text block doesn't fit.