PF/ARIA/BestPractices/Tooltips
Keyboard Support for Tooltips
Tooltips are popup messages typically triggered by moving a mouse over a control or widget causing a small popup window to appear with additional information about the control. For accessibility, the user should be able to activate tooltips using the keyboard. When a form control or widget receives keyboard focus, the tooltip popup should display. When the form control or widget loses focus, the tooltip should disappear.
See also discussion of tooltips.