Prevent doubly curved surface when moving vertex

Hi, are there a way to prevent doubly curved surface when moving vertex on a simple box?

Hello- currently no, at least not without splitting the face first (SplitFace) as you have here.

-Pascal

Hi, tnx for the reply, If I need to do the SplitFace after the edit, how do I straighten the curve ?

simplest way is with loft from one edge to your line, or extrude to point from the line to a corner