sets the view gravity
// equal sizes
webix.ui({
    cols:[
        { gravity:1, template:"left" },
        { gravity:1, template:"right" }
    ]
});
 
// the left area two times wider than the right one
webix.ui({
    cols:[
        { gravity:2, template:"left" },
        { gravity:1, template:"right" }
    ]
});
The parameter is used to set relative size proportions for the elements within the common parent container.