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G21: Ensuring that users are not trapped in content


All technologies which support interactive operation.

This technique relates to:


The objective of this technique is to ensure that keyboard users do not become trapped in a subset of the content that can only be exited using a mouse or pointing device. A common example is content rendered by plug-ins. Plug-ins are user agents that render content inside the user agent host window and respond to all user actions that takes place while the plug-in has the focus. If the plug-in does not provide a keyboard mechanism to return focus to the parent window, users who must use the keyboard may become trapped in the plug-in content.

This problem can be avoided by using one of the following mechanisms to provide a way for users to escape the subset of the content:

[begin add]

If the author uses a technology that allows users to enter the sub-content with keyboard and does not allow users to exit the sub-content with keyboard by default (i.e. it is not a feature of the web content technology or its user agents) then, in order to implement this technique the author would either build such a capability into their content or not use the technology. [2043]

[end add]



No resources available for this technique.

(none currently listed)



  1. tab through content from start to finish.

  2. check to see if keyboard focus is trapped in any of the content such that the person cannot move out of any part of the content and continue through the rest of the content.

Expected Results