Gutter = function(parentEl) {
    this.element = dom.createElement("div");
    this.element.className = "ace_layer ace_gutter-layer";
    parentEl.appendChild(this.element);
    this.setShowFoldWidgets(this.$showFoldWidgets);
    
    this.gutterWidth = 0;

    this.$breakpoints = [];
    this.$annotations = [];
    this.$decorations = [];
}
VirtualRenderer.setStyle(style) -> Void
- style (String): A class name

[Adds a new class, `style`, to the editor.]{: #VirtualRenderer.setStyle}