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
}
    /**
     * Display the given error message. The currently displayed message is saved
     * and will be redisplayed when the error message is set to
     * <code>null</code>.
     * 
     * @param newErrorMessage
     *            the newErrorMessage to display or <code>null</code>
     */
    public void setErrorMessage(String newErrorMessage) {
        
        if (errorMessage == null ? newErrorMessage == null : errorMessage
                .equals(newErrorMessage)) {
			return;
		}
        errorMessage = newErrorMessage;
         
        
        if (errorMessage == null) {
        	if(messageArea != null && !showingWarning){
           		setMessageAreaVisible(false);
         	}
            if (showingError) {
                
                showingError = false;
            }