The WSJT-X activity window is opened from the "View" menu, which is only shown when the
network is used to communicate with WSJT-X (set in the WSJT-X tab
of the Preferences window).
It displays the same information as
the main window, but for the call from WSJT-X's "DX Call" field.
It also has up to six buttons, if macros are configured in the
preferences, for setting the free text message in
WSJT-X
Clicking one of the buttons is equivalent to typing a new message (old contents are discarded) in to the WSJT-X free text message field or "Tx5" field (both are updated) and then clicking the "Now" radio button for the "Tx5" field if tab one is current or clicking the "Free msg" radio button if tab two is current.