### About the Converted Accessibility Tree
For several applications like Firefox or Thunderbird, you should first enable
```sh
gsettings set org.gnome.desktop.interface toolkit-accessibility true
```
to see their accessibility tree.
#### Example of AT
An example of a node:
```xml
```
An example of a tree:
```xml
...
...
```
#### Useful attributes
1. `name` - shows the name of application, title of window, or name of some
component
2. `attr:class` - somewhat the same role as `class` in HTML
3. `attr:id` - somewhat the same role as `id` in HTML
4. `cp:screencoord` - absolute coordinator on the screen
5. `cp:windowcoord` - relative coordinator in the window
6. `cp:size` - the size
Also several states like `st:enabled` and `st:visible` can be indicated. A full
state list is available at
.
#### How to use it in evaluation
See example `thunderbird/12086550-11c0-466b-b367-1d9e75b3910e.json` and
function `check_accessibility_tree` in `metrics/general.py`. You can use CSS
selector or XPath to reference a target nodes. You can also check its text
contents.
An example of a CSS selector:
```css
application[name=Thunderbird] page-tab-list[attr|id="tabmail-tabs"]>page-tab[name="About Profiles"]
```
This selector will select the page tab of profile manager in Thunderbird (if open).
For usage of CSS selector: . For usage of XPath: .
#### Manual check
You can use accerciser to check the accessibility tree on GNOME VM.
```sh
sudo apt install accerciser
```
### Additional Installation
Activating the window manager control requires the installation of `wmctrl`:
```bash
sudo apt install wmctrl
```
To enable recording in the virtual machine, you need to install `ffmpeg`:
```bash
sudo apt install ffmpeg
```