Only set MyStepPanel.LastAdjust if MyStepPanel isn't null

After StepRTB is resized verify that text has not scrolled out of view

PROMS/Volian.Controls.Library/StepRTB.cs

@@ -1076,7 +1076,11 @@ namespace Volian.Controls.Library
 					this.Size = szNew;
 					//Console.WriteLine("after {0}, {1}, {2}, {3}", Size, szNew, widthNew, Width);
 					if (heightOld != Height)
+					{
 						OnHeightChanged(this, new EventArgs());
+						if (ScrollPos.Y != 0) // Adjust ScrollPosition if it isn't Zero
+							ScrollPos = new Point(0, 0);
+					}
 				}
 			}
 		}