examples(micropython): add a few missing MP examples (#3672)

examples/others/gridnav/lv_example_gridnav_4.py

@@ -0,0 +1,36 @@
+def event_handler(e):
+    obj = e.get_target()
+    list = obj.get_parent()
+    print("Clicked: " + list.get_btn_text(obj))
+
+
+#
+# Simple navigation on a list widget
+#
+# It's assumed that the default group is set and
+# there is a keyboard indev
+
+list = lv.list(lv.scr_act())
+lv.gridnav_add(list, lv.GRIDNAV_CTRL.ROLLOVER)
+list.align(lv.ALIGN.LEFT_MID, 0, 10)
+lv.group_get_default().add_obj(list)
+
+for i in range(20):
+
+    # Add some separators too, they are not focusable by gridnav
+    if i % 5 == 0:
+        txt = "Section {:d}".format(i // 5 + 1)
+        # lv_snprintf(buf, sizeof(buf), "Section %d", i / 5 + 1);
+        list.add_text(txt)
+
+    txt = "File {:d}".format(i + 1)
+    #lv_snprintf(buf, sizeof(buf), "File %d", i + 1);
+    item = list.add_btn(lv.SYMBOL.FILE, txt)
+    item.add_event_cb(event_handler, lv.EVENT.CLICKED, None)
+    lv.group_remove_obj(item)  # The default group adds it automatically
+
+btn = lv.btn(lv.scr_act())
+btn.align(lv.ALIGN.RIGHT_MID, 0, -10)
+label = lv.label(btn)
+label.set_text("Button")
+