You can use grips to edit a dimensionally constrained object either by selecting the object, or by selecting the constraint. 
- Select a dimensionally constrained object. 
- Click one of its grips. 
- Press and release the Shift key to relax the dimensional constraint temporarily. 
- Continue the editing operation with the grip. 
or 
- Select a dimensional constraint. 
- Click one of its grips: - The square grips relocate the text 
- The arrow grips change the length of the object 
 
- Press Esc to cancel the selection.