add a PieceTable::Cursor to Window

src/gui/Window.cc

@@ -127,6 +127,7 @@ bool Window::create(std::shared_ptr<Buffer> buffer)
             cursor_bounds, sizeof(cursor_bounds));
 
     m_buffer = buffer;
+    m_cursor = m_buffer->piece_table->add_cursor();
     m_start_piece = m_buffer->piece_table->start_piece->next;
 
     resize();

src/gui/Window.h

@@ -40,6 +40,8 @@ protected:
 
     std::shared_ptr<glcxx::Buffer> m_cursor_buffer;
 
+    std::shared_ptr<PieceTable::Cursor> m_cursor;
+
     PieceTable::Piece * m_start_piece;
 };