Use redundant keyboard and mouse event handlers
Make sure specific mouse event handlers are duplicated to account for the keyboard
It is not uncommon for images and other active objects to change or be modified in response to a mouse event; images appears to be active or inactive, to change color, to be turned on or off. Links change color, or have their presentation altered. Tooltips, sub menus and tab panels fly out as the users’ mouse hovers over them, etc. Authors often fall into the trap of planning great interactions for the mouse, while failing to replicate the same behaviour for users who only use the keyboard. As a result, a lot of those behaviours are lost to anyone who does not or cannot use a mouse. Any effect achieved or conveyed to users as they roll their mouse over an image, graphic or object needs to be conveyed through other means to be considered accessible: so users who cannot use a mouse can still benefit from the planned interaction as well.
To do so, simply make sure that whenever the onMouseover and onMouseout event handlers are used to change a behaviour (when the mouse moves on top of or away [...]