# System Variables

System-wide configurations (file types icons, list of default desktop wallpapers, open with menu, etc.) are set in `src/lib/system.js`

For data that need to be communicated across the system, win32.run uses [Svelte Stores](https://svelte.dev/tutorial/writable-stores). (`src/lib/store.js`). These data structures allow any page to subscribe and listen to their changes.

**Example 1:** any page can request to launch a program with

```javascript
import { queueProgram } from '$lib/store.js'
queueProgram.set(program_details);
```

`src/routes/xp/work_space.svelte` listens to these requests and launches the requested program

```javascript
import { queueProgram } from '$lib/store.js'

queueProgram.subscribe(program_details => {
    if(program_details == null){
        return;
    }
    launch(program_details);
})
```

**Example 2:** the hard drive `hardDrive` (in src/lib/store.js) is also a Svelte Store (actually it's just the inventory of files and folders, the real files' contents are saved in IndexedDB).

Any *native* program can make updates to win32 hard drive with `hardDrive.update(...)` or `hardDrive.set(...).` (Though you should use utilities functions in `$lib/fs.js` like `fs.save_file, fs.del_fs, fs.new_fs_item`)

`src/routes/xp/programs/my_computer.svelte` subscribes to its changes and updates its UI accordingly


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