fix F2, F3 and F4 shortcuts

src/asammdf/gui/utils.py

@@ -272,7 +272,7 @@ def __init__(self, *args, **kwargs):
         self.thread_finished = True
         self.close_on_finish = True
         # Connect signal to "processEvents": Give the chance to "destroy" function to make his job
-        self.qfinished.connect(lambda: QtCore.QCoreApplication.processEvents())
+        self.qfinished.connect(self.processEvents)
 
     def run_thread_with_progress(self, target, args, kwargs, wait_here=False, close_on_finish=True):
         self.show()

src/asammdf/gui/widgets/file.py

@@ -1621,6 +1621,8 @@ def _create_window(self, event=None, window_type=None):
                 window_type = None
 
             disable_new_channels = dialog.disable_new_channels()
+        else:
+            disable_new_channels = False
 
         if window_type is None:
             return

src/asammdf/gui/widgets/mdi_area.py

@@ -1,4 +1,5 @@
 from copy import deepcopy
+import datetime
 from functools import partial
 import inspect
 import itertools
@@ -2761,10 +2762,15 @@ def _add_tabular_window(self, names):
             dfs.append(df)
 
         if not dfs:
-            return
+            signals = pd.DataFrame()
+            try:
+                start = self.mdf.header.start_time
+            except:
+                start = datetime.datetime.now()
+        else:
+            signals = pd.concat(dfs, axis=1)
 
-        signals = pd.concat(dfs, axis=1)
-        start = min(start)
+            start = min(start)
 
         for name in signals.columns:
             if name.endswith(