This property can be used to add a margin to the cells when rendering, so text is rendered smaller and can have more line breaks. The default value of 1.0 means normal cells. The bigger this value, the bigger the margins and the smaller the real cell width for rendering the text. You might want to make this value a little larger than 1 if autofitting and Excel is wrapping text that FlexCel fits into one line.
property TExcelFile.CellMarginFactor: Double