This was introduced in 3.x as 2.x does not have this issue. A CheckBox's input element is not vertically aligned with it's box label. The label appears to be aligned correctly, the actual checkbox input element is not.

This can be seen in the demo page here (look at the Music field label value): http://www.sencha.com/examples/#Exam...e:formsexample

Or via some sample code:
Code:
public class CheckBoxTest implements EntryPoint
{
   @Override
   public void onModuleLoad()
   {
      ContentPanel cp = new ContentPanel();
      cp.setPixelSize(500, 500);
      cp.setHeadingText("CheckBox Label Alignment Teset");
 
      CheckBox cb = new CheckBox();
      cb.setBoxLabel("Test CheckBox");
      TextButton tb = new TextButton("A Button!");
 
      ToolBar bar = new ToolBar();
      bar.add(tb);
      bar.add(new SeparatorToolItem());
      bar.add(cb);
 
      VerticalLayoutContainer vlc = new VerticalLayoutContainer();
      vlc.add(bar, new VerticalLayoutContainer.VerticalLayoutData(1, -1));
 
      CenterLayoutContainer clc = new CenterLayoutContainer();
      HTML html = new HTML("<h1>Some HTML!</h1>");
      clc.setWidget(html);
      vlc.add(clc, new VerticalLayoutContainer.VerticalLayoutData(1, 1));
 
      cp.setWidget(vlc);
      RootPanel.get().add(cp);
   }
}