protected void refreshColumnWidths() {
        int columnCount = getRealColumnCount();
        for (int i = 0; i < columnCount; i++) {
            doSetColumnWidth(i, getColumnWidth(i));
        }
    }
Get the thead element that contains the headers.
stroom-core-client-widget/src/main/java/com/google/gwt/user/cellview/client/AbstractCellTable.java