private void handleGroupChange() {
   int index;
   if (fGroupCombo != null) {
     index = fGroupCombo.getSelectionIndex();
   } else {
     index = fGroupComboPart.getSelectionIndex();
   }
   if (index != fGrouping) {
     // Refresh tree
     fGrouping = index;
     fTree.getControl().setRedraw(false);
     fTree.refresh(false);
     fTree.expandAll();
     updateCheckState();
     updateButtons();
     fTree.getControl().setRedraw(true);
   }
 }
  /* (non-Javadoc)
   * @see org.eclipse.pde.internal.ui.wizards.target.TargetDefinitionPage#targetChanged()
   */
  protected void targetChanged(ITargetDefinition definition) {
    super.targetChanged(definition);
    if (definition != null) {
      // When  If the page isn't open yet, try running a UI job so the dialog has time to finish
      // opening
      new UIJob(PDEUIMessages.TargetDefinitionContentPage_0) {
        public IStatus runInUIThread(IProgressMonitor monitor) {
          ITargetDefinition definition = getTargetDefinition();
          if (!definition.isResolved()) {
            try {
              getContainer()
                  .run(
                      true,
                      true,
                      new IRunnableWithProgress() {
                        public void run(IProgressMonitor monitor)
                            throws InvocationTargetException, InterruptedException {
                          getTargetDefinition().resolve(new ResolutionProgressMonitor(monitor));
                          if (monitor.isCanceled()) {
                            throw new InterruptedException();
                          }
                        }
                      });
            } catch (InvocationTargetException e) {
              PDECore.log(e);
            } catch (InterruptedException e) {
              fContentTree.setCancelled();
              return Status.CANCEL_STATUS;
            }
          }
          fContentTree.setInput(definition);
          fLocationTree.setInput(definition);
          if (definition.isResolved() && definition.getStatus().getSeverity() == IStatus.ERROR) {
            fLocationTab.setImage(
                PlatformUI.getWorkbench()
                    .getSharedImages()
                    .getImage(ISharedImages.IMG_OBJS_ERROR_TSK));
          } else {
            fLocationTab.setImage(null);
          }
          return Status.OK_STATUS;
        }
      }.schedule();
      String name = definition.getName();
      if (name == null) {
        name = EMPTY_STRING;
      }

      if (name.trim().length() > 0) fNameText.setText(name);
      else setMessage(PDEUIMessages.TargetDefinitionContentPage_8);

      fLocationTree.setInput(definition);
      fContentTree.setInput(definition);

      String presetValue = (definition.getOS() == null) ? EMPTY_STRING : definition.getOS();
      fOSCombo.setText(presetValue);
      presetValue = (definition.getWS() == null) ? EMPTY_STRING : definition.getWS();
      fWSCombo.setText(presetValue);
      presetValue = (definition.getArch() == null) ? EMPTY_STRING : definition.getArch();
      fArchCombo.setText(presetValue);
      presetValue =
          (definition.getNL() == null)
              ? EMPTY_STRING
              : LocaleUtil.expandLocaleName(definition.getNL());
      fNLCombo.setText(presetValue);

      IPath jrePath = definition.getJREContainer();
      if (jrePath == null || jrePath.equals(JavaRuntime.newDefaultJREContainerPath())) {
        fDefaultJREButton.setSelection(true);
      } else {
        String ee = JavaRuntime.getExecutionEnvironmentId(jrePath);
        if (ee != null) {
          fExecEnvButton.setSelection(true);
          fExecEnvsCombo.select(fExecEnvsCombo.indexOf(ee));
        } else {
          String vm = JavaRuntime.getVMInstallName(jrePath);
          if (vm != null) {
            fNamedJREButton.setSelection(true);
            fNamedJREsCombo.select(fNamedJREsCombo.indexOf(vm));
          }
        }
      }

      if (fExecEnvsCombo.getSelectionIndex() == -1)
        fExecEnvsCombo.setText(fExecEnvChoices.first().toString());

      if (fNamedJREsCombo.getSelectionIndex() == -1)
        fNamedJREsCombo.setText(VMUtil.getDefaultVMInstallName());

      updateJREWidgets();

      presetValue =
          (definition.getProgramArguments() == null)
              ? EMPTY_STRING
              : definition.getProgramArguments();
      fProgramArgs.setText(presetValue);
      presetValue =
          (definition.getVMArguments() == null) ? EMPTY_STRING : definition.getVMArguments();
      fVMArgs.setText(presetValue);

      fElementViewer.refresh();
    }
  }