The VB6’s SetStart, SelLength, and SetText properties have been renamed as SelectionStart, SelectionLength, and SelectionText under VB.NET, respectively.

There is also a minor difference in the behavior: the SelStart property indirectly resets the SelLength property to 0 and the SelectionText to an empty string, and ensures that the insertion point is visible inside the TextBox control. In VB.NET you have to invoke the ScrollToCaret method to bring the insertion point into the control’s visible area.

VB  Migration Partner correctly replicates the VB6 behavior under .NET.