SETMARGINS is not supported (or needed) in FMSLogo.
In other Logo environments, SETMARGINS clears the text screen and then arrange for all further printing to be shifted down and to the right according to the
margins input, effectively adding margins to the text screen.
Specifically, every time a newline character is printed (explicitly or implicitly) Logo types x_margin spaces, and on every invocation of SETCURSOR the margins are added to the input x and y coordinates.
(CURSOR reports the cursor position relative to the margins, so this shift is invisible to Logo programs.)
The input is a list of two numbers, as for SETCURSOR.
The purpose of this command is to accommodate the display of screens in lecture halls with inadequate TV monitors that miss the top and left edges of the screen. This is not necessary in FMSLogo, as the window can just be moved to the visible portion of the TV monitor.