[KevinH]

The following change just commited to Sigil master seems to fix this issue on my dev machine (a Mac). Hopefully the same fix will work for all platforms.

diff --git a/src/Tabs/FlowTab.cpp b/src/Tabs/FlowTab.cpp
index 47ab9d1..8a6deb6 100644
--- a/src/Tabs/FlowTab.cpp
+++ b/src/Tabs/FlowTab.cpp
@@ -112,6 +112,12 @@ FlowTab::~FlowTab()
     // No idea how that's possible but this prevents a segfault...
 
     disconnect(this, 0, 0, 0);
+
+    // or at least it used to, as this signal Modified still fires so try an explicit
+    // disconnect
+
+    disconnect(m_HTMLResource, SIGNAL(Modified()), this, SLOT(ResourceModified()));
+
     m_WellFormedCheckComponent->deleteLater();
 
     if (m_wBookView) {

If anyone can recreate this on other platforms by having the existing html toc open in a CodeView tab (and properly marked in the guide) and then running Tools->Table of Contents->Create Table of Contents, it would be helpful to know that. It would also be useful to know if this "fix" helps.

Thanks for the test case and bug report. I will delete the test case once we confirm the issue is fixed on all platforms.