Bug 137073 [Preferences] Encoding field editor never fires value change events
The class AbstractEncodingFieldEditor never fires VALUE property change events unless the validaty of the value has also changed. I will attach a patch that corrects the problem.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/AbstractEncodingFieldEditor.java
return current == null || current.length() == 0;
		}
		return encodingSetting.equals(current);
	}
	/**
	 * Return whether or not the default has been selected.
	 * 
	 * @return <code>true</code> if the default button has been selected.
	 */
	boolean isDefaultSelected() {
		return defaultEncodingButton.getSelection();
	}
	/**
	 * Set the title of the group to groupTitle. If this is not called a default
	 * title is used. If groupTitle is <code>null</code> the control will be
	 * unlabelled (by default a {@link Composite} instead of a {@link Group}.
	 * 
	 * <strong>NOTE</strong> this value must be set before
	 * {@link #createControl(Composite)} is called or it will be ignored.
	 * 
	 * @param groupTitle
	 *            The groupTitle to set.
     * @since 3.3
	 */
	public void setGroupTitle(String groupTitle) {
		this.groupTitle = groupTitle;
	}
}