Bug 273330 [JFace] Add API to MessageDialog to enable clients to use SWT.SHEET
A new style constant SWT.SHEET was added recently. Without adding new API in JFace, clients who are currently using the convenience methods MessageDialog.openWarning/Error/Information/Question/Confirmation would not be able to open these dialogs as sheets.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/MessageDialogWithToggle.java
"A message dialog with toggle may not have a null toggle button.");} 
        if (!button.isDisposed()) {
            final String text;
            if (toggleMessage == null) {
                text = JFaceResources
                        .getString("MessageDialogWithToggle.defaultToggleMessage"); 
            } else {
                text = toggleMessage;
            }
            button.setText(text);
            button.setSelection(toggleState);
        }
        this.toggleButton = button;
    }
    /**
     * A mutator for the text on the toggle button. The button will
     * automatically get updated with the new text, if it exists.
     * 
     * @param message
     *            The new text of the toggle button; if it is <code>null</code>,
     *            then used the default toggle message.
     */
    protected void setToggleMessage(String message) {
        this.toggleMessage = message;
        if ((toggleButton != null) && (!toggleButton.isDisposed())) {
            final String text;
            if (toggleMessage == null) {
                text = JFaceResources
                        .getString("MessageDialogWithToggle.defaultToggleMessage"); 
            } else {