Hello, Steven,

The possible solution that I can suggest in order to handle this unexpected behavior is close the editor once the scrollbar is clicked. Please use the following code snippet:

            this.radGridView1.TableElement.VScrollBar.MouseDown += VScrollBar_MouseDown;


        private void VScrollBar_MouseDown(object sender, MouseEventArgs e)
        {
            if (this.radGridView1.IsInEditMode)
            {
                this.radGridView1.EndEdit();
            }
        }

I hope this information helps. If you need any further assistance please don't hesitate to contact me. 

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik