The additions specified in your sublime-keymap book should lead to the expected behavior:
{ "keys": ["ctrl+b"], "command": "build", "args": { "variant": "" } }, { "keys": ["ctrl+shift+b"], "command": "build", "args": { "variant": "Run" } },
However, you can reassign the options list to alt + b:
{ "keys": ["alt+b"], "command": "build", "args": { "select": true } },
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