columnsAutoWidth

defines whether the width of columns is automatically adjusted to the width of their content

var grid = new dhx.Grid("grid_container", {
    columns: [// columns config],
    adjust: true,      data: dataset
});

Example

var grid = new dhx.Grid("grid_container", {
    columns: [// columns config],
    columnsAutoWidth: true,     data: dataset
});

At the moment "number" type defines the number of the last column that should be auto adjusted.