The GUI is "directly-connected" to the XLM72 and remains synchronized with the state of the device. In other words, changes that are made to the GUI immediately produce a change in the XLM72. You cannot configure a setting and then apply it to the device at a later time!
There are only two times that the GUI will not reflect the actual state of the device. Those two times are at startup and after the "Read" button has been pressed. At startup there is no communication with the module. To retrieve the state of the device and display it in the GUI, the user should press the "Get" button. This button synchronizes the state of the GUI to the state of the XLM. The other scenario is when the Read button has been pressed. In that case, a configuration file will be read and then its restored state will be represented in the GUI. At that point, the user can either discard the state or use it by pressing the "Get" or "Put" buttons, respectively.
The one final interesting aspect to this GUI is the "dt" parameter. This should be understood as being purely for the sake of the user. It is used for translating the raw parameter values to calibrated time values for display and adjusts for the length of the external delay cable being used.