Fix wrong scrolling (#6809)

numberZero · SmallJoker · commit 257626ceedc9 · 2017-12-21T20:58:06.000+01:00
diff --git a/src/gui/intlGUIEditBox.cpp b/src/gui/intlGUIEditBox.cpp
@@ -1431,13 +1431,10 @@ void intlGUIEditBox::calculateScrollPos()
 	}
 
 	// vertical scroll position
-	if (FrameRect.LowerRightCorner.Y < CurrentTextRect.LowerRightCorner.Y + VScrollPos)
-		VScrollPos = CurrentTextRect.LowerRightCorner.Y - FrameRect.LowerRightCorner.Y + VScrollPos;
-
-	else if (FrameRect.UpperLeftCorner.Y > CurrentTextRect.UpperLeftCorner.Y + VScrollPos)
-		VScrollPos = CurrentTextRect.UpperLeftCorner.Y - FrameRect.UpperLeftCorner.Y + VScrollPos;
-	else
-		VScrollPos = 0;
+	if (FrameRect.LowerRightCorner.Y < CurrentTextRect.LowerRightCorner.Y)
+		VScrollPos += CurrentTextRect.LowerRightCorner.Y - FrameRect.LowerRightCorner.Y; // scrolling downwards
+	else if (FrameRect.UpperLeftCorner.Y > CurrentTextRect.UpperLeftCorner.Y)
+		VScrollPos += CurrentTextRect.UpperLeftCorner.Y - FrameRect.UpperLeftCorner.Y; // scrolling upwards
 
 	// todo: adjust scrollbar
 	if (m_vscrollbar)
