Handle properly undo groups in embedded work areas

When a buffer is in an embedded work area (adv. find&replace), it is
not found by BufferList:::exists(), and therefore the undo group
created in GuiApplication::dispatch and in the handling of
LFUN_COMMAND_SEQUENCE will not be closed.. Crashes can ensue, as
described in Ubuntu bug:
https://bugs.launchpad.net/bugs/1737429

The solution is to introduce BufferList::isInternal and act on it.

Fixes bug #10847.

(cherry picked from commit 8b107f0490)

src/BufferList.cpp

@@ -279,6 +279,16 @@ bool BufferList::exists(FileName const & fname) const
 }
 
 
+bool BufferList::isInternal(Buffer const * b) const
+{
+	if (!b)
+		return false;
+	BufferStorage::const_iterator cit =
+		find(binternal.begin(), binternal.end(), b);
+	return cit != binternal.end();
+}
+
+
 bool BufferList::isOthersChild(Buffer * parent, Buffer * child)
 {
 	LASSERT(parent, return false);

src/BufferList.h

@@ -84,6 +84,9 @@ public:
 	/// returns true if the buffer is loaded
 	bool isLoaded(Buffer const * b) const;
 
+	/// returns true if the buffer is known as internal buffer
+	bool isInternal(Buffer const * b) const;
+
 	/// \return index of named buffer in buffer list
 	int bufferNum(support::FileName const & name) const;
 

src/Undo.cpp

@@ -562,7 +562,8 @@ void Undo::beginUndoGroup()
 	if (d->group_level_ == 0) {
 		// create a new group
 		++d->group_id_;
-		LYXERR(Debug::UNDO, "+++++++Creating new group " << d->group_id_);
+		LYXERR(Debug::UNDO, "+++++++ Creating new group " << d->group_id_
+		       << " for buffer " << &d->buffer_);
 	}
 	++d->group_level_;
 }
@@ -586,7 +587,8 @@ void Undo::endUndoGroup()
 	if (d->group_level_ == 0) {
 		// real end of the group
 		d->group_cur_before_ = CursorData();
-		LYXERR(Debug::UNDO, "-------End of group " << d->group_id_);
+		LYXERR(Debug::UNDO, "------- End of group " << d->group_id_
+		       << " of buffer " << &d->buffer_);
 	}
 }
 

src/frontends/qt4/GuiApplication.cpp

@@ -1407,7 +1407,7 @@ DispatchResult const & GuiApplication::dispatch(FuncRequest const & cmd)
 	updateCurrentView(cmd, dr);
 
 	// the buffer may have been closed by one action
-	if (theBufferList().isLoaded(buffer))
+	if (theBufferList().isLoaded(buffer) || theBufferList().isInternal(buffer))
 		buffer->undo().endUndoGroup();
 
 	d->dispatch_result_ = dr;
@@ -1883,7 +1883,7 @@ void GuiApplication::dispatch(FuncRequest const & cmd, DispatchResult & dr)
 			dispatch(func);
 		}
 		// the buffer may have been closed by one action
-		if (theBufferList().isLoaded(buffer))
+		if (theBufferList().isLoaded(buffer) || theBufferList().isInternal(buffer))
 			buffer->undo().endUndoGroup();
 		break;
 	}