Your JavaRanch name needs to be changed. It's not really my job to tell you this, but there you go.
The reason for the display is that tree nodes are actually JLabels, and those dots (aka an ellipsis ) are a "feature" of JLabel, when the JLabel is forced to occupy a smaller area than it would preffer. AFAIK JTree doesn't grow to accomodate long labels, so basically you may be screwed.
Of course, you could always subclass JTree and override Component.getPreferredSize() to fix this. (Or you could write a Component listener to call JComponent.setPreferredSize()). But there may be some serious difficulties in doing this, as JTree rendering is anything but trivial, and such a scheme would probably have to go through the entire tree, making it expensive.
While I doubt it, there might be something at:
http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html