When a JTextArea is removed from a JScrollPane viewport then
re-added after strings are inserted into the JTextArea's document, the
horizontal JScrollBar is not activated properly. The vertical
JScrollBar is OK. If horizontal JscrollBar is not active and the user
invokes the endLine functionality on a line too long for the view, the
viewport scrolls but leaves a shadow.

Using Swing 1.0.1 and JDK 1.1.5 - see attached test case.

To Reproduce: Open any file with lines longer than what can fit in your
JInternalFrame. The horizontal JScrollBar is not activated but the
vertical one is. See VisDebug.java lines 1547-1563.