About the Accessibility Viewer (aViewer)

The Accessibility Viewer (aViewer) is an inspection tool for Windows that displays the accessibility API information (MSAA, IAccessible2, UI Automation, ARIA, HTML DOM) exposed by web browsers to the operating system, and thus to any assistive technology (AT) such as screenreaders.

screenshot of aViewer showing the accessibility tree, accessibility API properties and HTML code panels.

Features

  • Exposes MSAA, IAccessible2 (in Firefox and Chrome), ARIA, HTML DOM and UI Automation (in Internet Explorer) properties.
  • Displays a navigable accessibility tree. The tree scope can be customized via the View menu.
  • Accessibility properties, accessibility tree and HTML code panes.
  • Customize which MSAA, IAccessible2 and UI Automation properties to display via the settings dialog:
  • settings dialog showing property customization 'use of properties' listbox, the font change button and the IAccessible2 registration buttons.

  • Show balloon tip with MSAA, IAccessible2 and HTML code information on element hover, focus or as you navigate the accessibility tree.
  • Information to display in the balloon tip can be customized by using the View menu ALT+VBalloon Tips sub-menu.
    screenshot of Submit button with associated balloon tip displaying MSAA information for the element.
  • Customize what to display via the View menu (ALT+V)
    'view' menu with display, collapse and treeview contents sub menus.
  • IAccessible2 relations are listed in the object information tree view
    aViewer screenshot
    What this means is that if an element has an associated label that is associated using the IAccessible2 labelledby relation type (for example, this relation is used extensively in Firefox) or it has any of the ARIA relationship attributes (also supported in Firefox) you can select the relation target in the tree view and the element it is referenced by will be highlighted in the page
    Screenshot showing a focused element , the listing in aViewer of its labelledby relation and its associated targets. One of the targets listed is selected and the referenced element is highlighted on the page.

The Accessibility Viewer (aViewer) toolbar

  1. Watch Focus F4 – Information will be displayed for the element that has focus
  2. Watch Cursor F5 – Information will be displayed for the element that is under the cursor
  3. Show Highlight Rectangle F6 – places a visible highlight rectangle around the element that is currently being inspected
  4. Show tooltip F3 – displays tooltip in context with MSAA information (note: accessible name for this button is not currently user friendly)
  5. Copy Text to Clipboard F7 – copies all the information currently displayed to the clipboard
  6. Focus Rectangle Only F8 – disables all features except the keyboard focus rectangle
  7. Navigate to Parent Object F9
  8. Navigate to First Child Object F10
  9. Navigate to Previous Sibling Object F11
  10. Navigate to Next Sibling Object F12
  11. Show Online Help F1 – opens the Accessibility Viewer (aViewer) help in a browser window.
  12. Desktop Mode – Disables HTML and ARIA inspection features.
  13. Settings –
    1. Modify displayed properties via the check boxes
    2. Change font and size
    3. In order to inspect IAccessible2 information the DLL needs to be registered on initial use.
      1. Register
      2. Unregister

Note: the settings and desktop mode don't currently have keyboard shortcuts, but can be activated using the keyboard by tabbing to the toolbar then using the arrow keys, then Space or Enter to enable/disable.

Known issues

  • The Accessibility Viewer (aViewer) does not work reliably with certain versions and combinations of browser and screenreader.
  • When navigating the page content in the browser (not via the accessibility tree), the balloon tips can only be displayed using keyboard navigation on focusable elements (any element will display a balloon tips using the mouse). This can be overcome by temporarily adding a tabindex=0 to all elements within a page.
  • The HTML code view works in Firefox and Internet Explorer, but not in Chrome, as this browser currently does not expose the required information. In Firefox the code view displays the innerHTML for the currently focused element, while in Internet Explorer, it displays the outerHTML.

Acknowledgements

The Accessibility Viewer (aViewer) is developed by Jun and Steve Faulkner (The Paciello Group, Europe), with support from Hans Hillen and Gez Lemon (The Paciello Group, Europe).

For feedback and suggestions, or to provide additional translations, please contact Steve Faulkner (sfaulkner@paciellogroup.com).

Terms of use

The Accessibility Viewer (aViewer) is freeware. It is made available for both personal and commercial use to help you determine the accessibility of your web content.

This work is licenced under a Creative Commons License Creative Commons Attribution No Derivatives 3.0 License

THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED WARRANTY. IN PARTICULAR, THE PACIELLO GROUP DOES NOT MAKE ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE RELIABILITY, QUALITY, OR MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. ADDITIONALLY, THE PACIELLO GROUP DOES NOT GUARANTEE THAT USE OF THIS SOFTWARE WILL ENSURE THE ACCESSIBILITY OF YOUR WEB CONTENT OR THAT YOUR WEB CONTENT WILL COMPLY WITH ANY SPECIFIC WEB ACCESSIBILITY STANDARD.