JAL-2609 fully erase scale above, tidy code change

diff --git a/src/jalview/gui/SeqCanvas.java b/src/jalview/gui/SeqCanvas.java
index 6c6e87a..d82f69a 100755 (executable)
--- a/src/jalview/gui/SeqCanvas.java
+++ b/src/jalview/gui/SeqCanvas.java
@@ -838,10 +838,12 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
        * white fill region of scale above and hidden column markers
        * (to support incremental fast paint of image)
        */
+      g.translate(labelWidthWest, 0);
       g.setColor(Color.white);
       g.fillRect(0, ypos - wrappedSpaceAboveAlignment, viewportWidth
               * charWidth + labelWidthWest, wrappedSpaceAboveAlignment);
       g.setColor(Color.black);
+      g.translate(-labelWidthWest, 0);
 
       g.translate(labelWidthWest, 0);
 
@@ -1666,7 +1668,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
         // larger than the visible window
         ViewportRanges vpRanges = av.getRanges();
         scrollX = (int) evt.getNewValue() - (int) evt.getOldValue();
-        int range = vpRanges.getEndRes() - vpRanges.getStartRes() + 1;
+        int range = vpRanges.getViewportWidth();
         if (scrollX > range)
         {
           scrollX = range;