The radar view widget is a passive awareness display that will track
the movements of users in a two-dimensional document. The radar responds
to changes in GroupKit's awareness model to update its display.
Typically, the radar view will also be used in conjunction with GroupKit's
scrollbars, which generate changes in the awareness model. This is
seen in the following code fragment:
grid [canvas .c -scrollregion "0 0 2000 2000"] \
-column 0 -row 0 -sticky nwes
grid [gk::scrollbar .hs -orient horizontal -command ".c xview" \
-multiuser no] -column 0 -row 1 -sticky we
grid [gk::scrollbar .vs -command ".c yview" -multiuser no] \
-column 1 -row 0 -rowspan 2 -sticky ns
grid [gk::radar .r] -column 2 -row 0