Open Sublime Text console and run:
sublime.log_input(True); sublime.log_commands(True); sublime.log_result_regex(True)
When you type the command you should see what is happening on the console.
key evt: shift+alt+1
command: set_layout {"cells": [[0, 0, 1, 1]], "cols": [0.0, 1.0], "rows": [0.0, 1.0]}
key evt: shift+alt+2
command: set_layout {"cells": [[0, 0, 1, 1], [1, 0, 2, 1]], "cols": [0.0, 0.5, 1.0], "rows": [0.0, 1.0]}
key evt: shift+alt+1
command: set_layout {"cells": [[0, 0, 1, 1]], "cols": [0.0, 1.0], "rows": [0.0, 1.0]}
What do you see?

