Adding disabled styling for CheckBox as part of creating a default GWT css.
Patch by: jlabanca
Review by: ecc

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@1657 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/src/com/google/gwt/user/client/ui/CheckBox.java b/user/src/com/google/gwt/user/client/ui/CheckBox.java
index dfaf33a..7d6ebd7 100644
--- a/user/src/com/google/gwt/user/client/ui/CheckBox.java
+++ b/user/src/com/google/gwt/user/client/ui/CheckBox.java
@@ -27,6 +27,7 @@
  * <h3>CSS Style Rules</h3>
  * <ul class='css'>
  * <li>.gwt-CheckBox { }</li>
+ * <li>.gwt-CheckBox-disabled { Applied when Checkbox is disabled }</li>
  * </ul>
  * <p>
  * <h3>Example</h3>
@@ -138,6 +139,11 @@
   @Override
   public void setEnabled(boolean enabled) {
     DOM.setElementPropertyBoolean(inputElem, "disabled", !enabled);
+    if (enabled) {
+      removeStyleDependentName("disabled");
+    } else {
+      addStyleDependentName("disabled");
+    }
   }
 
   @Override