diff --git a/nw/gui/elements/doceditor.py b/nw/gui/elements/doceditor.py
index dfbecf63..f5f22e2a 100644
--- a/nw/gui/elements/doceditor.py
+++ b/nw/gui/elements/doceditor.py
@@ -185,6 +185,7 @@ class GuiDocEditor(QTextEdit):
             tHandle = self.theHandle
             self.clearEditor()
             self.loadText(tHandle)
+            self.updateDocMargins()
         else:
             self.clearEditor()
 
@@ -241,6 +242,35 @@ class GuiDocEditor(QTextEdit):
 
         return True
 
+    def updateDocMargins(self):
+        """Automatically adjust the margins so the text is centred, but
+        only if Config.textFixedW is set to True.
+        """
+
+        if self.mainConf.textFixedW or self.theParent.isZenMode:
+            vBar = self.verticalScrollBar()
+            if vBar.isVisible():
+                sW = vBar.width()
+            else:
+                sW = 0
+            if self.theParent.isZenMode:
+                tW = self.mainConf.zenWidth
+            else:
+                tW = self.mainConf.textWidth
+            wW = self.width()
+            tM = int((wW - sW - tW)/2)
+            if tM < self.mainConf.textMargin:
+                tM = self.mainConf.textMargin
+        else:
+            tM = self.mainConf.textMargin
+
+        docFormat = self.qDocument.rootFrame().frameFormat()
+        docFormat.setLeftMargin(tM)
+        docFormat.setRightMargin(tM)
+        self.qDocument.rootFrame().setFrameFormat(docFormat)
+
+        return
+
     ##
     #  Setters and Getters
     ##
@@ -403,33 +433,11 @@ class GuiDocEditor(QTextEdit):
         return
 
     def resizeEvent(self, theEvent):
-        """Automatically adjust the margins so the text is centred, but
-        only if Config.textFixedW is set to True.
+        """If the text editor is resize, we must make sure the document
+        has its margins adjusted according to user preferences.
         """
         QTextEdit.resizeEvent(self, theEvent)
-
-        if self.mainConf.textFixedW or self.theParent.isZenMode:
-            vBar = self.verticalScrollBar()
-            if vBar.isVisible():
-                sW = vBar.width()
-            else:
-                sW = 0
-            if self.theParent.isZenMode:
-                tW = self.mainConf.zenWidth
-            else:
-                tW = self.mainConf.textWidth
-            wW = self.width()
-            tM = int((wW - sW - tW)/2)
-            if tM < self.mainConf.textMargin:
-                tM = self.mainConf.textMargin
-        else:
-            tM = self.mainConf.textMargin
-
-        docFormat = self.qDocument.rootFrame().frameFormat()
-        docFormat.setLeftMargin(tM)
-        docFormat.setRightMargin(tM)
-        self.qDocument.rootFrame().setFrameFormat(docFormat)
-
+        self.updateDocMargins()
         return
 
     ##
diff --git a/nw/guimain.py b/nw/guimain.py
index 2f8d943a..ba275963 100644
--- a/nw/guimain.py
+++ b/nw/guimain.py
@@ -707,6 +707,10 @@ class GuiMain(QMainWindow):
         statusbar and menu.
         """
 
+        if self.docEditor.theHandle is None:
+            logger.error("No document open, so not activating Zen Mode")
+            return False
+
         self.isZenMode = not self.isZenMode
         if self.isZenMode:
             logger.debug("Activating Zen mode")
@@ -714,12 +718,15 @@ class GuiMain(QMainWindow):
             logger.debug("Deactivating Zen mode")
 
         isVisible = not self.isZenMode
-        self.viewPane.setVisible(isVisible)
         self.treePane.setVisible(isVisible)
         self.statusBar.setVisible(isVisible)
-        # self.mainMenu.setVisible(isVisible)
 
-        return
+        if self.viewPane.isVisible():
+            self.viewPane.setVisible(False)
+        elif self.docViewer.theHandle is not None:
+            self.viewPane.setVisible(True)
+
+        return True
 
     def toggleFullScreenMode(self):
         """Main GUI full screen mode. The mode is tracked by the flag