Some users read text or press keys very slowly and do not respond to events as quickly as the average user. Avoid displaying critical feedback or messages briefly and then automatically removing them because many users cannot read or respond to them. Similarly, limit your use of time-out based interfaces. If you do include a time-based interface, always provide a way for users to configure the time-out.
Also, avoid displaying or hiding information based on the movement of the pointer, unless it is part of a standard system interface (for example, tooltips). Although such techniques can benefit some users, they may not be available for those using accessibility utilities. If you do provide such support, consider making these features optional so that users can turn them on or off when a screen review utility is installed.
Similarly, you should avoid using general navigation to trigger operations, because users of accessibility aids may need to navigate through all controls. For example, basic TAB keyboard navigation in a dialog box should not activate actions associated with a control, such as setting a check box or carrying out a command button. However, navigation can be used to facilitate further user interaction, such as validating user input or opening a drop-down control.