diff --git a/app.py b/app.py
index 9b06295..caa2cdc 100644
--- a/app.py
+++ b/app.py
@@ -14,17 +14,28 @@ try:
   import plotly.io as pio
   import plotly as ply
   import plotly.subplots
+  import local_file_picker
 except ModuleNotFoundError as e:
   print('Module `plotly` not found.')
   exit(1)
 
-NAME = 'tempplot'
-FILENAME = './data/20260420213656.txt'
-fig = None
-plot = None
-label_file = None
-label_file_fmt = 'tempplot: {filename}'
-# label_file_fmt = 'tempplot: {os.path.basename(filename)}'
+pio.templates["plotly_light"] = pgo.layout.Template(
+  layout = pio.templates["plotly_white"].layout)
+#pio.templates["plotly_light"].layout['scene']['xaxis']['gridcolor'] = 'gray'
+pio.templates["plotly_light"].layout['xaxis']['gridcolor'] = 'lightgray'
+pio.templates["plotly_light"].layout['xaxis']['zerolinecolor'] = 'lightgray'
+pio.templates["plotly_light"].layout['yaxis']['gridcolor'] = 'lightgray'
+pio.templates["plotly_light"].layout['yaxis']['zerolinecolor'] = 'lightgray'
+  
+ELM = {
+  'name': 'tempplot',
+  'filename': './data/20260420213656.txt',
+  'label_file_fmt': 'file: {filename}',
+  #'label_data_len_fmt': 'data points (rendered): {num}',
+  'label_data_len_fmt': 'data points: {num} (rendered), {numa} (total)',
+  'plotly_light': 'plotly_light',
+  'plotly_dark': 'plotly_dark',
+}
 
 def main_cli():
   import argparse
@@ -67,19 +78,16 @@ def np2pgo(x, y, label=None):
     res.update({'name': label})
   return res
 
-# def str2date(x):
-#   return datetime.datetime.strptime(x.decode('utf-8'), '%Y%m%d%H%M%S')
-
-import local_file_picker
 async def pick_file() -> None:
   result = await local_file_picker.local_file_picker('./data', multiple=False)
   # ui.notify(f'You chose {result}')
-  filename = result[-1]
-  update_data(filename)
-  label_file.set_text(label_file_fmt.format(filename=os.path.basename(filename)))
+  if result:
+    filename = result[-1]
+    ELM['filename'] = filename
+    # update_data()  # see timer below
+    ELM['label_file'].set_text(ELM['label_file_fmt'].format(filename=os.path.basename(filename)))
 
-def get_data(filename=FILENAME):
-  print(f"filename: {filename}")
+async def get_data(filename=ELM['filename']):
   data = np.genfromtxt(fname=filename, skip_header=1)
 
   if len(data) > 0 and len(data[0]) > 6:
@@ -92,93 +100,97 @@ def get_data(filename=FILENAME):
       0: lambda x: datetime.datetime.strptime(x, '%Y%m%d%H%M%S')},
     names=names, encoding='utf-8'
   )
-  print(data.shape)
-  print(data['time'])
-  #data[:, 0] = np.array(data[:, 0], dtype='datetime64')
-  #print(data.time)
   return data
 
-def update_data(filename=FILENAME):
-  data = get_data(filename)
+async def update_data():
+  filename=ELM['filename']
+  data_all = await get_data(filename)
+  data = data_all
+  # time_range = ELM['number_time_range'].value
+  time_range = app.storage.user['time_range']
+  if time_range is not None and time_range > 0:
+    # delta = datetime.datetime.now() - data['time']
+    delta = data['time'][-1] - data['time']
+    data = data[np.where(delta <= datetime.timedelta(hours=time_range))]
+  print(filename, data_all.shape, data.shape)
+  ELM['label_data_len'].set_text(ELM['label_data_len_fmt'].format(num=len(data), numa=len(data_all)))
   
-  fig.data = []
-  plot.visible = False
-  plot.update()
+  ELM['fig'].data = []
+  ELM['plot'].visible = False
+  ELM['plot'].update()
 
-  fig.add_trace(pgo.Scatter(**np2pgo(data['time'], data['ts'], 'Setp'))) 
-  fig.add_trace(pgo.Scatter(**np2pgo(data['time'], data['ta'], 'Temp A')))
-  fig.add_trace(pgo.Scatter(**np2pgo(data['time'], data['tb'], 'Temp B')))
+  ELM['fig'].add_trace(pgo.Scatter(**np2pgo(data['time'], data['ts'], 'Setp'))) 
+  ELM['fig'].add_trace(pgo.Scatter(**np2pgo(data['time'], data['ta'], 'Temp A')))
+  ELM['fig'].add_trace(pgo.Scatter(**np2pgo(data['time'], data['tb'], 'Temp B')))
   if len(data) > 0 and len(data[0]) > 6:
-    fig.add_trace(pgo.Scatter(**np2pgo(data['time'], data['tc'], 'Temp C')))
-    fig.add_trace(pgo.Scatter(**np2pgo(data['time'], data['td'], 'Temp D')))
+    ELM['fig'].add_trace(pgo.Scatter(**np2pgo(data['time'], data['tc'], 'Temp C')))
+    ELM['fig'].add_trace(pgo.Scatter(**np2pgo(data['time'], data['td'], 'Temp D')))
 
-  fig.add_trace(pgo.Scatter(**np2pgo(data['time'], data['hp'], 'Heat')),
-                row=2, col=1)
+  ELM['fig'].add_trace(pgo.Scatter(**np2pgo(data['time'], data['hp'], 'Heat')),
+                       row=2, col=1)
 
-  plot.visible = True
-  plot.update()
+  ELM['plot'].visible = True
+  ELM['plot'].update()
 
 @ui.page('/')
-def index():
-  global fig, plot, label_file
+async def index():
+  await ui.context.client.connected()
 
-  # data = get_data()
+  # initialize objects
+  ELM['fig'] = ply.subplots.make_subplots(rows=2, cols=1)
 
-  #
-  fig = ply.subplots.make_subplots(rows=2, cols=1)
-
-  #
+  # render header
   ui.context.client.content.classes('h-[100vh]')
   ui.add_head_html('''<meta name="viewport", content="width=device-width, initial-scale=1">
 <meta name="mobile-web-app-capable" content="yes">''')
 
   dark_mode = ui.dark_mode().bind_value(app.storage.user, 'dark_mode')
-  #ui.button('Dark', on_click=dark.enable)
-  #ui.button('Light', on_click=dark.disable)
-  ui.switch(
-    'Dark mode', on_change=lambda: fig.update_layout(template='plotly_dark' if dark_mode.value else 'plotly_white')
-  ).bind_value(app.storage.user, 'dark_mode').props('icon="dark_mode"')
-  print(dark_mode.value)
 
   ui.colors(primary='#4888c4')
-  
-  ui.button('Choose file', on_click=pick_file, icon='folder')
 
-  label_file = ui.label(label_file_fmt.format(filename=os.path.basename(FILENAME)))
+  with ui.row(align_items="center").classes('w-full'):
+    ui.button('Choose file', on_click=pick_file, icon='folder')
 
-#   range_t = ui.range(
-#     min=data['time'][0].timestamp(), max=data['time'][-1].timestamp(),
-#     # on_change=lambda e: fig.update_xaxes(
-#     #   range=[str(datetime.datetime.fromtimestamp(e.value["min"])),
-#     #          str(datetime.datetime.fromtimestamp(e.value["max"]))]),
-#   )
-#   ui.label().bind_text_from(
-#     range_t, 'value',
-#     backward=lambda v: (
-#         f'min: {datetime.datetime.fromtimestamp(v["min"])}\n\
-# max: {datetime.datetime.fromtimestamp(v["max"])}'),
-#   ).style('white-space: pre-wrap')
+    ELM['number_time_range'] = ui.number(
+      label='time range', value=6, format='%.2f', min=0, step=0.5,
+      suffix='h',
+      # on_change=lambda e: update_data(),  # see timer below
+    ).props('clearable').bind_value(app.storage.user, 'time_range').classes('w-32')
+
+    ELM['switch_timer'] = ui.switch('auto-refresh').bind_value(app.storage.user, 'timer')
+
+    ui.space()
+    
+    ui.switch(
+      'Dark mode', on_change=lambda: (
+        ELM['fig'].update_layout(
+          template=ELM['plotly_dark'] if dark_mode.value else ELM['plotly_light']),
+        'plot' in ELM and ELM['plot'].update())
+    ).bind_value(app.storage.user, 'dark_mode').props('icon="dark_mode"')
+
+  with ui.row():
+    ELM['label_file'] = ui.label(
+      ELM['label_file_fmt'].format(filename=os.path.basename(ELM['filename'])))
+    ELM['label_data_len'] = ui.label(ELM['label_data_len_fmt'].format(num=0, numa=0))
 
   pio.templates.default = 'plotly_dark'
-  # fig = pgo.Figure()
-  fig.update_layout(
+  # ELM['fig'] = pgo.Figure()
+  ELM['fig'].update_layout(
     height=600,
     #template='plotly_white'
-    template='plotly_dark' if dark_mode.value else 'plotly_white',
+    template=ELM['plotly_dark'] if dark_mode.value else ELM['plotly_light'],
   )
-  plot = ui.plotly(fig).classes('w-full')
+  ELM['plot'] = ui.plotly(ELM['fig']).classes('w-full')
 
-  update_data()
-
-  # print(fig.full_figure_for_development().layout.xaxis.range)
-  # ('2026-04-20 21:36:56', '2026-04-21 10:40:53')
-  # print(fig.full_figure_for_development().layout.xaxis.range[0])
-  # print(type(fig.full_figure_for_development().layout.xaxis.range[0]))
+  # update_data()
+  ui.timer(0, lambda: update_data(), once=True)
+  ELM['timer'] = ui.timer(2.0, lambda: update_data(), immediate=False)
+  ELM['switch_timer'].bind_value_to(ELM['timer'], 'active')
 
 def main_gui(args):
   ui.run(
-    host=args.host, port=int(args.port), title=NAME,
-    #dark=True,
+    host=args.host, port=int(args.port), title=ELM['name'],
+    dark=False,
     native=False,
     show=False, storage_secret='tempview')
 
diff --git a/local_file_picker.py b/local_file_picker.py
index 00fb505..e5288e0 100644
--- a/local_file_picker.py
+++ b/local_file_picker.py
@@ -1,4 +1,4 @@
-# https://github.com/zauberzeug/nicegui/blob/main/examples/local_file_picker/local_file_picker.py
+# based on https://github.com/zauberzeug/nicegui/blob/main/examples/local_file_picker/local_file_picker.py
 import platform
 from pathlib import Path
 
@@ -30,9 +30,19 @@ class local_file_picker(ui.dialog):
         with self, ui.card():
             self.add_drives_toggle()
             self.grid = ui.aggrid({
-                'columnDefs': [{'field': 'name', 'headerName': 'File'}],
-                'rowSelection': {'mode': 'multiRow' if multiple else 'singleRow'},
-            }, html_columns=[0]).classes('w-96').on('cellDoubleClicked', self.handle_double_click)
+                'columnDefs': [{
+                  'field': 'name', 'headerName': 'File', 'sort': 'desc',
+                  'filter': 'agTextColumnFilter', 'floatingFilter': True,
+                }],
+                'rowSelection': {
+                  'mode': 'multiRow' if multiple else 'singleRow',
+                  #'checkboxes': True if multiple else False,
+                  'enableClickSelection': True,
+                },
+                'selectionColumnDef': {'width': 28, 'cellStyle': {'textAlign': 'center'} },  # will be width+20 and min 48
+            }, html_columns=[0], theme='balham').classes('w-96').on('cellDoubleClicked', self.handle_double_click)
+            #\
+            #.on('cellClicked', self.handle_click)
             with ui.row().classes('w-full justify-end'):
                 ui.button('Cancel', on_click=self.close).props('outline')
                 ui.button('Ok', on_click=self._handle_ok)