Updating dhtmlx from 2.6 to 4.1

Hi,
We are using dhtmlx 2.6 for our product. Now we want to Update it to 4.1.
If we directly incorporate it, will it break any features ?
To make it work, do we need to handle any changes ?

Check
docs.dhtmlx.com/3.6/doku.php?id= … ersion_3.0

and
docs.dhtmlx.com/migration__index.html