Distances, midpoints & selection's width/height
Measuring distances between objects
Toggle on "Specifies distance between objects" to measure horizontal/vertical distances between objects. You must select at least two objects to measure the distance.
Measuring distances between objects' midpoints
Toggle on "Specifies distance between objects' midpoints" to measure horizontal/vertical distances between objects' midpoints. You must select at least two objects to measure the distance.
Tips: When generating labels for midpoint distances, you can select "Lines extend to midpoint of objects" in the dimension lines setting to make the lines point to the midpoint of the objects, which helps illustrate the distance between midpoints.
Measuring the width/height of the whole selection
Toggle on "Specifies height/width of the selection" to measure the width and height of the outer boundaries of the current selection of objects.