Hi Quintain,
It already is provided! It sounds as though you have got the Angle Snap off. Go to Settings / Program Settings / Drawing Aids. The Angle is usually set to 15 degrees with the Snap on, so you can always get a straight line (unless you deviate more than 15 degrees of course). You will also a find an ANGLESNAP on the Status Bar which just turns it of and on in a single click.
Allan