public leading : Number
An integer that represents the amount of vertical space in pixels (called leading) between lines. The default value is null, which indicates that the property is undefined.
The following example creates a text field and sets the leading to 10.
var my_fmt:TextFormat = new TextFormat();
my_fmt.leading = 10;
this.createTextField("my_txt", 1, 100, 100, 100, 100);
my_txt.multiline = true;
my_txt.wordWrap = true;
my_txt.border = true;
my_txt.text = "This is my first text field object text";
my_txt.setTextFormat(my_fmt);