jur,
thanks for the tip about tint2, will have that in mind if/when similar case reoccurs.
jls_legalize,
in fact I did try with xystray, but it never came properly up, there was an X error msg, not remembering for sure if it segfaulted.
Assuming incompatibility of xystray with jwm tray's <Dock> item, I also tried after commenting latter out and restarting jwm, and when that did not work with flwm and finally after killing wm without any wm whatsoever, but xystray still failed to come up.
The fact that xystray errored without any wm running makes me wonder if the very fact of a "lost" systray icon per se could prevent xystray from running...