diff --git a/README.md b/README.md
index a4474d3..5ec7f45 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-[![Download the latest release](docs/img/download-button.png)](https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.7.pyzw)
+[![Download the latest release](docs/img/download-button.png)](https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.8.pyzw)
 [![Changelog](docs/img/changelog-button.png)](docs/changelog.md)
 [![News](docs/img/news-button.png)](https://github.com/peter88213/novelibre/discussions/1)
 [![Online help](docs/img/help-button.png)](https://peter88213.github.io/nvhelp-en/)
@@ -81,10 +81,10 @@ I use the program myself and fix errors immediately if I notice any. As far as I
 
 ### Default: Executable Python zip archive
 
-Download the latest release [novelibre_v4.11.7.pyzw](https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.7.pyzw)
+Download the latest release [novelibre_v4.11.8.pyzw](https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.8.pyzw)
 
-- Launch *novelibre_v4.11.7.pyzw* by double-clicking (Windows/Linux desktop),
-- or execute `python novelibre_v4.11.7.pyzw` (Windows), resp. `python3 novelibre_v4.11.7.pyzw` (Linux) on the command line.
+- Launch *novelibre_v4.11.8.pyzw* by double-clicking (Windows/Linux desktop),
+- or execute `python novelibre_v4.11.8.pyzw` (Windows), resp. `python3 novelibre_v4.11.8.pyzw` (Linux) on the command line.
 
 #### Important
 
@@ -100,9 +100,9 @@ the zip file.
 
 ### Alternative: Zip file
 
-The package is also available in zip format: [novelibre_v4.11.7.zip](https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.7.zip)
+The package is also available in zip format: [novelibre_v4.11.8.zip](https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.8.zip)
 
-- Extract the *novelibre_v4.11.7* folder from the downloaded zipfile "novelibre_v4.11.7.zip".
+- Extract the *novelibre_v4.11.8* folder from the downloaded zipfile "novelibre_v4.11.8.zip".
 - Move into this new folder and launch *setup.pyw* by double-clicking (Windows/Linux desktop), 
 - or execute `python setup.pyw` (Windows), resp. `python3 setup.pyw` (Linux) on the command line.
 
diff --git a/VERSION b/VERSION
index 5579ba3..4df252a 100644
--- a/VERSION
+++ b/VERSION
@@ -1,3 +1,3 @@
 [LATEST]
-version = 4.11.7
-download_link = https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.7.pyzw
+version = 4.11.8
+download_link = https://github.com/peter88213/novelibre/raw/main/dist/novelibre_v4.11.8.pyzw
diff --git a/dist/novelibre_v4.11.7.pyzw b/dist/novelibre_v4.11.7.pyzw
deleted file mode 100644
index 700aeab..0000000
Binary files a/dist/novelibre_v4.11.7.pyzw and /dev/null differ
diff --git a/dist/novelibre_v4.11.7.zip b/dist/novelibre_v4.11.7.zip
deleted file mode 100644
index 90a0159..0000000
Binary files a/dist/novelibre_v4.11.7.zip and /dev/null differ
diff --git a/dist/novelibre_v4.11.8.pyzw b/dist/novelibre_v4.11.8.pyzw
new file mode 100644
index 0000000..376ff4a
Binary files /dev/null and b/dist/novelibre_v4.11.8.pyzw differ
diff --git a/dist/novelibre_v4.11.8.zip b/dist/novelibre_v4.11.8.zip
new file mode 100644
index 0000000..38b15e8
Binary files /dev/null and b/dist/novelibre_v4.11.8.zip differ
diff --git a/docs/changelog.md b/docs/changelog.md
index 25c91f2..817e706 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -8,6 +8,12 @@
 
 See the [GitHub "Features" project](https://github.com/users/peter88213/projects/14).
 
+### Version 4.11.8
+
+- Fix a bug where an exception is raised when trying to add a parent element to the tree while the project is locked. 
+
+Based on novxlib 4.7.2
+
 ### Version 4.11.7
 
 - Fix HTML report title display.
diff --git a/i18n/de.po b/i18n/de.po
index b520b3c..d78c3a7 100644
--- a/i18n/de.po
+++ b/i18n/de.po
@@ -3,9 +3,9 @@
 #
 msgid ""
 msgstr ""
-"Project-Id-Version: 4.11.7\n"
-"POT-Creation-Date: 2024-10-16 10:40:19\n"
-"PO-Revision-Date: 2024-10-16 10:40:19\n"
+"Project-Id-Version: 4.11.8\n"
+"POT-Creation-Date: 2024-10-17 18:08:32\n"
+"PO-Revision-Date: 2024-10-17 18:08:32\n"
 "Last-Translator: Peter Triesberger\n"
 "Language: de\n"
 "MIME-Version: 1.0\n"
diff --git a/i18n/locale/de/LC_MESSAGES/novelibre.mo b/i18n/locale/de/LC_MESSAGES/novelibre.mo
index 792473e..8ab5aae 100644
Binary files a/i18n/locale/de/LC_MESSAGES/novelibre.mo and b/i18n/locale/de/LC_MESSAGES/novelibre.mo differ
diff --git a/i18n/messages.pot b/i18n/messages.pot
index e7d4cdb..9c3106e 100644
--- a/i18n/messages.pot
+++ b/i18n/messages.pot
@@ -3,8 +3,8 @@
 #
 msgid ""
 msgstr ""
-"Project-Id-Version: 4.11.7\n"
-"POT-Creation-Date: 2024-10-16 10:40:19\n"
+"Project-Id-Version: 4.11.8\n"
+"POT-Creation-Date: 2024-10-17 18:08:32\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language: LANGUAGE\n"
diff --git a/src/nvlib/controller/nv_controller.py b/src/nvlib/controller/nv_controller.py
index 474d81a..bfdeaeb 100644
--- a/src/nvlib/controller/nv_controller.py
+++ b/src/nvlib/controller/nv_controller.py
@@ -303,11 +303,13 @@ def add_parent(self, event=None):
         if self._mdl.prjFile is None:
             return
 
-        if not self.check_lock():
-            try:
-                selection = self._ui.tv.tree.selection()[0]
-            except:
-                return
+        if self.check_lock():
+            return
+
+        try:
+            selection = self._ui.tv.tree.selection()[0]
+        except:
+            return
 
         if selection.startswith(SECTION_PREFIX):
             self.add_chapter(targetNode=selection)
@@ -1069,15 +1071,17 @@ def set_character_status(self, isMajor, elemIds=None):
             isMajor: bool -- If True, make the characters major. Otherwise, make them minor.
             elemIds: list of character IDs to process.
         """
-        if not self.check_lock():
-            if elemIds is None:
-                try:
-                    elemIds = self._ui.tv.tree.selection()
-                except:
-                    return
+        if self.check_lock():
+            return
 
-            self._ui.tv.open_children(CR_ROOT)
-            self._mdl.set_character_status(isMajor, elemIds)
+        if elemIds is None:
+            try:
+                elemIds = self._ui.tv.tree.selection()
+            except:
+                return
+
+        self._ui.tv.open_children(CR_ROOT)
+        self._mdl.set_character_status(isMajor, elemIds)
 
     def set_level(self, newLevel, elemIds=None):
         """Set chapter or stage level.
@@ -1086,14 +1090,16 @@ def set_level(self, newLevel, elemIds=None):
             newLevel: int -- New level to be set.
             elemIds: list of IDs to process.
         """
-        if not self.check_lock():
-            if elemIds is None:
-                try:
-                    elemIds = self._ui.tv.tree.selection()
-                except:
-                    return
+        if self.check_lock():
+            return
+
+        if elemIds is None:
+            try:
+                elemIds = self._ui.tv.tree.selection()
+            except:
+                return
 
-            self._mdl.set_level(newLevel, elemIds)
+        self._mdl.set_level(newLevel, elemIds)
 
     def set_completion_status(self, newStatus, elemIds=None):
         """Set section completion status (Outline/Draft..).
@@ -1102,15 +1108,17 @@ def set_completion_status(self, newStatus, elemIds=None):
             newStatus: int -- New section status to be set.        
             elemIds: list of IDs to process.            
         """
-        if not self.check_lock():
-            if elemIds is None:
-                try:
-                    elemIds = self._ui.tv.tree.selection()
-                except:
-                    return
+        if self.check_lock():
+            return
 
-            self._ui.tv.open_children(elemIds[0])
-            self._mdl.set_completion_status(newStatus, elemIds)
+        if elemIds is None:
+            try:
+                elemIds = self._ui.tv.tree.selection()
+            except:
+                return
+
+        self._ui.tv.open_children(elemIds[0])
+        self._mdl.set_completion_status(newStatus, elemIds)
 
     def set_type(self, newType, elemIds=None):
         """Set section or chapter type Normal).
@@ -1119,15 +1127,17 @@ def set_type(self, newType, elemIds=None):
             newType: int -- New type to be set.
             elemIds: list of IDs to process.
         """
-        if not self.check_lock():
-            if elemIds is None:
-                try:
-                    elemIds = self._ui.tv.tree.selection()
-                except:
-                    return
+        if self.check_lock():
+            return
+
+        if elemIds is None:
+            try:
+                elemIds = self._ui.tv.tree.selection()
+            except:
+                return
 
-            self._ui.tv.open_children(elemIds[0])
-            self._mdl.set_type(newType, elemIds)
+        self._ui.tv.open_children(elemIds[0])
+        self._mdl.set_type(newType, elemIds)
 
     def show_report(self, suffix):
         """Create HTML report for the web browser.
diff --git a/tools/build.py b/tools/build.py
index bc7c8b8..f57a27d 100644
--- a/tools/build.py
+++ b/tools/build.py
@@ -12,7 +12,7 @@
 sys.path.insert(0, f'{os.getcwd()}/../../novelibre/tools')
 from package_builder import PackageBuilder
 
-VERSION = '4.11.7'
+VERSION = '4.11.8'
 
 
 class ApplicationBuilder(PackageBuilder):