diff --git a/vmcompact/app.py b/vmcompact/app.py
index d798b0a..f151201 100644
--- a/vmcompact/app.py
+++ b/vmcompact/app.py
@@ -65,7 +65,7 @@ class App(tk.Tk):
         self.styletable = ttk.Style()
         self._vmr = vmr
 
-        # start pdirty watcher
+        # start watchers, initialize level arrays
         self.upd_pdirty()
         self.strip_levels = self.target.strip_levels
         self.bus_levels = self.target.bus_levels
@@ -135,6 +135,8 @@ class App(tk.Tk):
         )
         self._vban = vban
         self.kind = kind
+        self.strip_levels = self.target.strip_levels
+        self.bus_levels = self.target.bus_levels
 
         self._make_top_level_frames()
 
@@ -184,7 +186,7 @@ class App(tk.Tk):
         self.comp_strip = [not a == b for a, b in zip(self.strip_levels, _strip_levels)]
         self.comp_bus = [not a == b for a, b in zip(self.bus_levels, _bus_levels)]
 
-        self.ldirty = any(self.comp_strip) or any(self.comp_bus)
+        self.ldirty = any(any(l) for l in (self.comp_strip, self.comp_bus))
         if self.ldirty:
             self.strip_levels = _strip_levels
             self.bus_levels = _bus_levels
diff --git a/vmcompact/channels.py b/vmcompact/channels.py
index ade928a..afc9438 100644
--- a/vmcompact/channels.py
+++ b/vmcompact/channels.py
@@ -346,15 +346,15 @@ class ChannelFrame(ttk.Frame):
 
         # create labelframes
         if is_strip:
-            self.strips = [
+            self.strips = tuple(
                 Strip(self, i, self.identifier)
                 for i in range(self.phys_in + self.virt_in)
-            ]
+            )
         else:
-            self.buses = [
+            self.buses = tuple(
                 Bus(self, i, self.identifier)
                 for i in range(self.phys_out + self.virt_out)
-            ]
+            )
 
         # position label frames. destroy any without label text
         self.labelframes = self.strips if is_strip else self.buses
@@ -367,6 +367,12 @@ class ChannelFrame(ttk.Frame):
                 self.columnconfigure(i, minsize=0)
                 labelframe.grid_remove()
 
+        for i, labelframe in enumerate(self.labelframes):
+            labelframe.grid(row=0, column=i)
+            if not labelframe.cget("text"):
+                self.columnconfigure(i, minsize=0)
+                labelframe.grid_remove()
+
     @property
     def target(self):
         """returns the current interface"""