Hi Nacho,

AFIAK there is no such property in TextBox nor in Label. You can use this
functionality out of the box only when you draw text directly using Graphics
objects (see StringFormat.Trimming property). However in the case where you
want to trim with ellipsis at the end of the string it is not hard to
calculate the text length by yourself. Other trimming are not hard either,
but need more work.

So here is a sample that does this

string longStr = "This is some string that doesn't fit in the textbox";
  Font f = this.textBox1.Font;
  Rectangle rect = textBox1.ClientRectangle;
  int charFitted;
  int linesFitted;
  using(Graphics g = textBox1.CreateGraphics())
  {

   StringFormat sf = new StringFormat(StringFormatFlags.NoWrap);
   sf.LineAlignment = StringAlignment.Center;
   sf.Alignment = StringAlignment.Near;
   sf.Trimming = StringTrimming.EllipsisCharacter;
   g.MeasureString(longStr, f, rect.Size, sf, out charFitted, out
linesFitted);
  }
  textBox1.Text = longStr.Substring(0, charFitted) + ((charFitted <
longStr.Length)?"...":"");

The results are not the best possible, but are pretty decent.