Extension Developer: Custom 'when' clauses for keyboard bindings & menus

[warrenbuckley]

I have come across the when property for KeyBindings & Menus in the Contribution points in the package.json file of my extension, but I would love to be able to based inside some logic of my extension to enable/disable showing & hiding certain menu options.

https://code.visualstudio.com/docs/getstarted/keybindings#_when-clause-contexts

I could achieve this with a configuration but this seems wrong & a bit hacky for my situation, as I would not want the user to configure this value.

"configuration": {
    "type": "object",
    "title": "IIS Express Settings",
    "properties": {
        "iisexpress.serverRunning": {
            "type": "boolean",
            "default": false,
            "description": "This property is not to be set or used in settings.config its just used to display the correct menu items if the server is running or not"
        }
    }
}

So in my extension I could update the config value when IIS Express Server is running so that the Restart & Stop Server commands are only visible in the menu & keyboard bindings etc.

Can I suggest some form of API to allow the when property to work with some developer defined boolean that could be toggled from the extension developers codebase

[jrieken]

There is an API-command which allows you set a context key. See #10471 (comment).

Closing this as dupe of #10471 which should be considered for April