For many objects, the distance fields in quick property boxes and settings dialogs display a ruler icon to the far right when you hover with the mouse over the field, or when the field is in focus:

The Measure and Apply is a tool which could prove helpful in use cases such as:

• Matching the length of one wall to another without needing to copy and paste values in the quick properties or the Wall Settings dialog.
• Matching and fixing floor section distances for imported AutoCAD drawings.
• Setting default values of distance fields to an exact measurement of another object in the drawing area.

Its functionality is similar to using the Ruler icon in the 2D or 3D toolbar to get a quick measurement, but with the additional feature of applying the measured distance.

To describe how this tool is used, we will match the length of a new wall to that of an existing wall. To do so, follow these steps:

1. Make sure to have a wall with the desired dimensions in the drawing area. (Wall 80")
2. Then add another wall and drag out to the drawing area.  
3. Left click once to set the starting point. 
4. Move the cursor to the ruler icon in the quick properties box and click, or use the Ctrl + M keyboard shortcut, to start the measure tool. A circle is now attached to the cursor.
5. Move the circle to one end of the exisiting wall and click to place a starting point.
6. Move the circle to the other end of wall and click for an end point.
7. The length of the first wall is now applied to the second wall.