@9214 pointed you to Linux GTK builds of Red. My example was tested in macOS so haven't tried it on Linux but you'll need GTK & 32bit compatibility libraries installed for it to work.
Rebol/View as always worked on Linux though you will also need 32bit compat + Freetype libraries - https://stackoverflow.com/questions/34524169/rebol-2-stopped...
And there's a 64-bit Rebol 3 with R3-GUI from Atronix, which should only need Freetype library installed - https://www.atronixengineering.com/downloads
The VID has changed a little bit over time. Here's the example in Rebol2 View...
Rebol []
view layout compose [
across
text (rejoin [{The sum of } figs: [1 2 3 4] { is: }])
answer: text {......}
return
button "Push me to calculate" 200x20 [
answer/text: to-string sum figs
show answer
]
]
And here it is in Rebol 3 / R3-GUI...
load-gui
view compose [
hgroup [
text (rejoin [{The sum of } figs: [1 2 3 4] { is: }])
answer: text {......}
return
button "Push me to calculate" on-click [
set-face answer to-string sum figs
]
]
]
Both scripts above worked fine on my Ubuntu 18 Linux.
NB. Rebol doesn't come with a SUM function so here's one defined...
sum: func [s /local total] [
total: 0
forall s [total: total + s/1]
total
]