GNOME Wireless Applet

build failed because of missing header file
applet-widget.h. Googling indicated that this
is supposed to be supplied by gnome-core-devel,
but I have installed this package (a la Debian),
yet the needed file is still absent. Is there
another package which I should install?

By the way, the wireless applet used to be provided
automatically with gnome-panel, and I was using it
very happily until the last time I upgraded
gnome-panel, and found to my dismay that this applet
was no longer supplied with the rest of the applets.
It was working perfectly---why did someone decide to
remove it?