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About this Add-on
Install this add-on as you would any other add-on.
When you install the add-on for the first time, the HTML5 toggle button is placed in the toolbar palette. Before you can actually use the HTML5 toggle button, you need to move the button from the toolbar palette onto a toolbar using the Customize Toolbar option
Toggling HTML5 support is also available as a menu item under the Tools menu and via a Ctrl-Alt-H shortcut.
If you have other add-ons installed and do not see the the HTML5 button on the toolbar palette, first check to see if the menu option works.