Steps that do not change alignment must not be considered as modifications

The following use cases must be fixed.

Use case 1:

1. Open an alignment.
2. Select a region.
3. Hold the left mouse button.
4. Move the region to the right and move it back on the same place.
5. Release the button.
   Current state: formally the alignment is the same, but the "Undo" button on the toolbar is available and the alignment overview is redrawn.
   Expected state:
   • The "Undo" button is NOT available.
   • The overview is NOT redrawn.
   • There is no "Alignment Modification Confirmation" dialog.

Use case 2:

1. Open an alignment.
2. Double-click on a character.
   Current state: the alignment overview is redrawn.
   Expected state:
   • The overview is NOT redrawn.
   • There is no "Alignment Modification Confirmation" dialog.