Bug 144556 [Dialogs] TitleAreaDialog fails to properly recreate when an instance is reopened
When a TitleAreaDialog is created, opened, closed and opened again on the same instance the messageArea is not properly checked against disposal when it is accessed in setWarningMessage throwing an SWTException for disposed when the message area is updated the second time the dialog is opened.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/TitleAreaDialog.java
messageLabel.setFont(JFaceResources.getDialogFont());
        messageLabelHeight = messageLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
        
        leftFillerLabel = new Label(titleArea, SWT.CENTER);
        leftFillerLabel.setBackground(background);
        setLayoutsForNormalMessage(verticalSpacing, horizontalSpacing);
        determineTitleImageLargest();
        
        return titleArea;
    }
    /**
     * Determine if the title image is larger than the title message and message
     * area. This is used for layout decisions.
     */
    private void determineTitleImageLargest() {
        int titleY = titleImageLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
        int verticalSpacing = convertVerticalDLUsToPixels(IDialogConstants.VERTICAL_SPACING);
        int labelY = titleLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
        labelY += verticalSpacing;
        labelY += messageLabelHeight;
        labelY += verticalSpacing;
        titleImageLargest = titleY > labelY;
    }
    /**
     * Set the layout values for the messageLabel, messageImageLabel and
     * fillerLabel for the case where there is a normal message.
     * 
     * @param verticalSpacing
     *            int The spacing between widgets on the vertical axis.
     * @param horizontalSpacing