Preserve dynamic layout flag after changing viewer input

The state of the "dynamic layout" flag should be restored after the
viewer input has changed, rather than always be set again. This flag can
only be "false" if explicitly unset by the user. It should therefore
remain disabled until explicitly enabled again.

org.eclipse.zest.core/src/org/eclipse/zest/core/viewers/GraphViewer.java

@@ -121,9 +121,10 @@ public void mouseDoubleClick(MouseEvent e) {
 
  @Override
  protected void inputChanged(Object input, Object oldInput) {
+ boolean dynamicLayoutEnabled = graph.isDynamicLayoutEnabled();
  graph.setDynamicLayout(false);
  super.inputChanged(input, oldInput);
- graph.setDynamicLayout(true);
+ graph.setDynamicLayout(dynamicLayoutEnabled);
  graph.applyLayout();
  }