WSJT-X/doc/user_guide/controls-functions-main-window.adoc

// Status=review
The following buttons appear just under the decoded text windows on
the main screen:

//.Main UI Controls
image::main-ui-controls.png[align="left",width=650,alt="Main UI Controls"]

* *Log QSO* raises a dialog window pre-filled with known information
about a QSO you have nearly completed.  You can edit or add to this
information before clicking *OK* to log the QSO.  If you check *Prompt
me to log QSO* on the *Setup* menu, the program will raise the
confirmation screen automatically when you send a message containing
73.

//.Log QSO Window
image::log-qso.png[align="center",alt="Log QSO"]

* *Stop* will terminate normal data acquisition in case you want to
freeze the waterfall or open and explore a previously recorded audio
file.

* *Monitor* restarts normal receive operation.  This button is
highlighted in green when the _WSJT-X_ is receiving.  If you are
using CAT control, toggling *Monitor* OFF relinquishes control of the
rig; if _Monitor returns to last used frequency_ is selected
on the *Settings | General* tab, toggling *Monitor* back ON will
return to the original frequency.

* *Erase* clears the right-hand decoded text window. 
Double-clicking *Erase* clears both text windows.

* *Decode* tells the program to repeat the decoding procedure at the
Rx frequency (green marker on waterfall scale), using the most recently
completed sequence of received data.  

* *Enable Tx* toggles the program into automatic T/R sequencing mode
and highlights the button in red.  A transmission will start at
the beginning of the selected (odd or even) sequence, or immediately
if appropriate.  A transmission will not be started any later than 24
s into a UTC minute.

* *Halt Tx* terminates a transmission in progress and disables
automatic T/R sequencing.

* *Tune* may be used to switch into Tx mode and generate an
unmodulated carrier at the specified Tx frequency (red marker on
waterfall scale).  This process may be useful for adjusting an antenna
tuner.  The button is highlighted in red while *Tune* is active.
Toggle the button a second time or click *Halt Tx* to terminate the
*Tune* process.