Full Screen Mode
Starting from the version 3.3, the library includes the fullscreen extension.
This extension provides an API that expands the component to the fullscreen mode, by using FullScreen API whenever possible (the list of supported browsers).

For older browsers it simply allows extending Gantt to 100% of window size.
To activate the fullscreen support, enable the fullscreen plugin via the gantt.plugins method:
gantt.plugins({
fullscreen: true
});
The component itself doesn't have a UI control that toggles this mode, you need to add it somewhere to your page or copy the one from example:
<input id="fullscreen_button" type="button" value="Toggle Fullscreen"/>
<script>
var button = document.getElementById("fullscreen_button");
button.addEventListener("click", function(){
if (!gantt.getState().fullscreen) {
// expanding the gantt to full screen
gantt.expand();
}
else {
// collapsing the gantt to the normal mode
gantt.collapse();
}
}, false);
</script>
A click on the ready icon will change the gantt's size from original to 'full screen' and vice versa.