To stretch a dimension, you must include the appropriate definition points in the selection set. You can most easily include them by turning on grips and selecting the object so that the grips are highlighted.
In the following example, the center point of dimension text is a definition point, so you can move the dimension text anywhere as long as you select this point (shown selected with crossing selection in the illustration).
If you move the text so that it no longer requires the dimension line to be split, the dimension line rejoins.
When you edit dimensioned objects, you must include the relevant dimension definition points in the selection set for updating to work. Definition points are the points that determine the dimension location. If you resize a dimensioned object, you need to include the definition point in the resizing operation to ensure that the dimensions stay associative, that is, that they are updated.
The definition points for each type of dimension are circled in the following illustration. The middle point of the dimension text is a definition point for all dimension types.
If no angle vertex is shown, AutoCAD LT places definition points at the ends of the lines that form the angle. In the two-line angular example, because an arc is being dimensioned, AutoCAD LT places a definition point at the center of the arc.
Definition points are drawn on a special layer named DEFPOINTS, which is not plotted. To plot definition points, rename the DEFPOINTS layer. AutoCAD LT creates a new DEFPOINTS layer for any subsequent dimensions in your drawing.
Some editing commands change the definition points of the dimension. For example, the definition points of a stretched or scaled dimension change because the object itself has changed. If the dimension is copied or arrayed, the definition points remain the same, because the dimensioned object has not been changed.