When editing large file (for example java/awt/Component.java) in JEditorPane, the text gets messed up when crossing some frontier (on java/awt/Component.java it was approximately 2300 lines). The original report against NetBeans is here:
http://www.netbeans.org/issues/show_bug.cgi?id=18022

Steps to reproduce:
1. Download attached example, compile it and run it.
2. Put some very big file (for example java/awt/Component.java) into the clipboard.
3. Paste it into test app (via Ctrl-V).
4. The text will be probably messed up now.
5. Try to scroll with the editor, some edits and so on.
You will see that under some barier, the text is messed up, above it it is OK.

This is reproducible only on Linux, neither on Solaris nor on Windows.
The Linux is RedHat 7.1, Window Manager was GNOME.
The JDK used is:
java -version:
java version "1.4.0-beta3"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta3-b83)
Java HotSpot(TM) Client VM (build 1.4.0-beta3-b83, mixed mode)