With Puppy Linux 2.17 (JWM 1.8) I could open a password-protected Excel-format spreadsheet using Gnumeric. The sheet would open in a new window and a corresponding task would appear on the task bar. From Puppy 4 (JWM 2.0.1) this does not work correctly. The window opens as before, but no indication of that task appears on the taskbar, so once the window is minimised it cannot be restored again. Well, there is a workaround - restart JWM and the task bar is updated to show the Gnumeric task. It looks like has changed between Puppy 2.17 and Puppy 4 which has caused this unfortunate task loss.
After testing version combinations of JWM and Gnumeric versions it looks like a change in Gnumeric has caused the problem, but the Gnumeric team think that it is an underlying window management issue and they have no means of solving it without help from the JWM developer.
Refer to http://www.murga-linux.com/puppy/viewtopic.php?p=284359 and http://bugzilla.gnome.org/show_bug.cgi?id=575462 for screen shots and more details.