This is on two lines so TheIde has the option of GUI or MT.
If it is on one line:
"" = "GUI MT";
the only option is GUI MT which apparently correct.
Since I got the thread working I did not change that back to two lines to see if the app would build.
There have been many posts regarding help documentation.
A download of the "Manual", "Book" or similar should have higher priority to promote Upp.
The "Help" in TheIde that comes with Upp should be better.