ags: NixOS compatibility; Partially migrate to new AgsStack syntax

.config/ags/widgets/sideright/calendar.js

@@ -146,11 +146,11 @@ const CalendarWidget = () => {
 const defaultShown = 'calendar';
 const contentStack = Widget.Stack({
     hexpand: true,
-    items: [
-        ['calendar', CalendarWidget()],
-        ['todo', TodoWidget()],
-        // ['stars', Widget.Label({ label: 'GitHub feed will be here' })],
-    ],
+    children: {
+        'calendar': CalendarWidget(),
+        'todo': TodoWidget(),
+        // 'stars': Widget.Label({ label: 'GitHub feed will be here' }),
+    },
     transition: 'slide_up_down',
     transitionDuration: 180,
     setup: (stack) => Utils.timeout(1, () => {

.config/ags/widgets/sideright/notificationlist.js

@@ -122,10 +122,10 @@ export default (props) => {
     const listContents = Stack({
         transition: 'crossfade',
         transitionDuration: 150,
-        items: [
-            ['empty', notifEmptyContent],
-            ['list', notifList]
-        ],
+        children: {
+            'empty': notifEmptyContent,
+            'list': notifList,
+        },
         setup: (self) => self
             .hook(Notifications, (self) => self.shown = (Notifications.notifications.length > 0 ? 'list' : 'empty'))
         ,

.config/ags/widgets/sideright/sideright.js

@@ -25,9 +25,10 @@ const timeRow = Box({
             className: 'txt-small txt',
             setup: (self) => self
                 .poll(5000, label => {
-                    execAsync(['bash', '-c', `uptime -p | sed -e 's/up //;s/ hours,/h/;s/ minutes/m/'`]).then(upTimeString => {
-                        label.label = `Uptime: ${upTimeString}`;
-                    }).catch(print);
+                    execAsync(['bash', '-c', `w | sed -n '1p' | cut -d, -f1 | cut -d' ' -f4-`])
+                        .then(upTimeString => {
+                            label.label = `Uptime: ${upTimeString}`;
+                        }).catch(print);
                 })
             ,
         }),

.config/ags/widgets/sideright/todolist.js

@@ -202,10 +202,10 @@ const UndoneTodoList = () => {
 const todoItemsBox = Widget.Stack({
     vpack: 'fill',
     transition: 'slide_left_right',
-    items: [
-        ['undone', UndoneTodoList()],
-        ['done', todoItems(true)],
-    ],
+    children: {
+        'undone': UndoneTodoList(),
+        'done': todoItems(true),
+    },
 });
 
 export const TodoWidget = () => {