Problem
The JTextArea used for messages extends all the time
Solution
The Java client message pane (a JTextPane) does not seem to work fine. It seems to extend all the time, making the other areas in the panel smaller and smaller. Never put a JTextArea or a JTable directly into a JPanel. Put a JScrollPane instead. Then put the JTextArea or JTable directly into the JScrollPanel. You also have to change the verticalScrollbarPolicy of the JScrollPane to VERTICAL_SCROLLBAR_ALWAYS,otherwise it does not work.