Add refresh interval as option in settings

files/system-monitor-graph@rcassani/desklet.js

@@ -26,6 +26,8 @@ MyDesklet.prototype = {
         // initialize settings
         this.settings = new Settings.DeskletSettings(this, this.metadata["uuid"], desklet_id);
         this.settings.bindProperty(Settings.BindingDirection.IN, "type", "type", this.on_setting_changed);
+        this.settings.bindProperty(Settings.BindingDirection.IN, "refresh-interval", "refresh_interval", this.on_setting_changed);
+
 
         // initialize desklet GUI
         this.setupUI();

files/system-monitor-graph@rcassani/settings-schema.json

@@ -27,5 +27,18 @@
         "type": "colorchooser",
         "default": "rgba(50,168,82,1.0)",
         "description": "Line color"
+    },
+    "refresh-interval": {
+        "type": "spinbutton",
+        "default": 2,
+        "step": 1,
+        "min": 1,
+        "max": 30,
+        "units": "seconds",
+        "description": "Refresh interval",
+        "tooltip": "Increase or decrease refresh interval in seconds."
     }
+
+
+
 }