From 82d3afb85161e0746c2136251eced5d7046225ca Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Tue, 19 Jul 2016 23:31:07 -0400
Subject: [PATCH] Gtkmm2ext::Pane: attempt to track child lifetime, since Gtkmm
 2.4 doesn't do this correctly

---
 libs/gtkmm2ext/gtkmm2ext/pane.h |  6 +++++-
 libs/gtkmm2ext/pane.cc          | 28 +++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/libs/gtkmm2ext/gtkmm2ext/pane.h b/libs/gtkmm2ext/gtkmm2ext/pane.h
index dfe2ef7ffe..9612da08d2 100644
--- a/libs/gtkmm2ext/gtkmm2ext/pane.h
+++ b/libs/gtkmm2ext/gtkmm2ext/pane.h
@@ -46,10 +46,11 @@ class LIBGTKMM2EXT_API Pane : public Gtk::Container
   public:
 	struct Child
 	{
+		Pane* pane;
 		Gtk::Widget* w;
 		int32_t minsize;
 
-		Child (Gtk::Widget* widget, uint32_t ms) : w (widget), minsize (ms) {}
+		Child (Pane* p, Gtk::Widget* widget, uint32_t ms) : pane (p), w (widget), minsize (ms) {}
 	};
 
 	typedef std::list<Child> Children;
@@ -108,6 +109,9 @@ class LIBGTKMM2EXT_API Pane : public Gtk::Container
 	void add_divider ();
 	void handle_child_visibility ();
 	bool fract_is_ok (Dividers::size_type, float fract);
+
+	static void* notify_child_destroyed (void*);
+	void* child_destroyed (Gtk::Widget*);
 };
 
 class LIBGTKMM2EXT_API HPane : public Pane
diff --git a/libs/gtkmm2ext/pane.cc b/libs/gtkmm2ext/pane.cc
index 867912d540..3eda140c57 100644
--- a/libs/gtkmm2ext/pane.cc
+++ b/libs/gtkmm2ext/pane.cc
@@ -48,6 +48,7 @@ Pane::Pane (bool h)
 Pane::~Pane ()
 {
 	for (Children::iterator c = children.begin(); c != children.end(); ++c) {
+		c->w->remove_destroy_notify_callback (&(*c));
 		c->w->unparent ();
 	}
 }
@@ -140,9 +141,14 @@ Pane::handle_child_visibility ()
 void
 Pane::on_add (Widget* w)
 {
-	children.push_back (Child (w, 0));
+	children.push_back (Child (this, w, 0));
 
 	w->set_parent (*this);
+	/* Gtkmm 2.4 does not correctly arrange for ::on_remove() to be called
+	   for custom containers that derive from Gtk::Container. So ... we need
+	   to ensure that we hear about child destruction ourselves.
+	*/
+	w->add_destroy_notify_callback (&children.back(), &Pane::notify_child_destroyed);
 
 	w->signal_show().connect (sigc::mem_fun (*this, &Pane::handle_child_visibility));
 	w->signal_hide().connect (sigc::mem_fun (*this, &Pane::handle_child_visibility));
@@ -152,11 +158,31 @@ Pane::on_add (Widget* w)
 	}
 }
 
+void*
+Pane::notify_child_destroyed (void* data)
+{
+	Child* child = reinterpret_cast<Child*> (data);
+	return child->pane->child_destroyed (child->w);
+}
+
+void*
+Pane::child_destroyed (Gtk::Widget* w)
+{
+	for (Children::iterator c = children.begin(); c != children.end(); ++c) {
+		if (c->w == w) {
+			children.erase (c);
+			break;
+		}
+	}
+	return 0;
+}
+
 void
 Pane::on_remove (Widget* w)
 {
 	for (Children::iterator c = children.begin(); c != children.end(); ++c) {
 		if (c->w == w) {
+			w->remove_destroy_notify_callback (&(*c));
 			w->unparent ();
 			children.erase (c);
 			break;
-- 
2.30.2