Create a custom and accessible panel, styled entirely with CSS.
An accessible panel:
By default a panel creates buttons as divs. In this example the
createControlMarkup panel function is overridden to create
a more accessible markup for the buttons. See the accessible-panel.js
source to see how this is done.
Note: in IE 8, when a button is pressed its content shifts by 1 pixel. This is a known IE8 bug, with known workarounds. No workaround is applied in this example though.