Bug Windows Disappear In Taskbar

Under Linux is a bug that makes your iDempiere windows disappear from the taskbar. The bug comes when you open a modal (transient) dialog like a find window or a file dialog. After opening and closing some of them you have much less windows in your taskbar than on your desktop.

I collect my informations on this page. If someone knows how to solve that issue for a lightweight window manager (I prefer xfce4 environment with xfwm) that runs well remote in a LTSP environment please tell me (User:TBayen).

What can you do if hit by this?

A fast solution is to change the virtual desktop (and come back)
You can still access all windows via alt-Tab
If you change a window to full-size it reappears in the taskbar
I fixed this bug by upgrading to OpenJDK7 - this is the easiest and most future proof solution

What I have not tried myself but might work:

exchange your window manager :-( because Compiz seems to have solved that (I failed with xfwm and metacity in Debian testing at January 2013 - I am not sure if is is anisue of the windowmanager or from the panel)
- german page how to exchange the window manager from Ubuntu wiki
- Article Run Compiz with Xfce4
I use OpenJDK6. Perhaps it is solved in a newer version. (update: tried OpenJDK7 and it worked)

How comes and who cares?

I seems to be a bug in Java.
It happens with many bigger programs that open many windows. You can find here a description what happens from a window manager's view.
At ubuntu pages is a bug entry (User:CarlosRuiz described it for ADempiere) that is marked as solved for compiz window manager.
Compiz has a patch for this issue

How to debug?

You can try and look at org.compiere.apps.search.Find in the Swing plugin. But I am afraid you will find nothing because the bug sits deeper in the native part of the Java Toolkit.