A Resizable and Scrollable Leaflet Control Panel.

<link rel="stylesheet" href="dist/Leaflet.ResizableControl.css" />
<script src="dist/Leaflet.ResizableControl.js"></script>
<script>
            ...
    		var resizableControl = new L.ResizableControl({
                position: 'bottomleft',
                minimizedHeight: 40,
                minimizedWidth: 0.1,
                enlargedHeight: 0.6,
                enlargedWidth: 0.4,
                enlargeCallback: function(e) {},
                minimizeCallback: function(e) {},
                contentClassName: "resizable-control-content",
                scrollPaneClassName: "resizable-control-scrollpane",
                className: "resizable-control-container",
                jscrollpane: true,
                appendOnAdd: function(divElement) {}
            });
    		map.addControl(resizableControl);
            ...
</script>

It's also possible to include Leaflet.ResizableControl.js as AMD module.