reproducible segfault in "edit" mode for a query

* Query against an empty table (SELECT * FROM SomeTable)
* Switch to edit mode on the result view
* Right click anywhere on the result view.
* Segfault.

GDB Backtrace (no app symbols):
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1228308352 (LWP 20721)]
0xb78a54c6 in Gtk::TreeView::set_cu...

* Query against an empty table (SELECT * FROM SomeTable)
* Switch to edit mode on the result view
* Right click anywhere on the result view.
* Segfault.

GDB Backtrace (no app symbols):
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1228308352 (LWP 20721)]
0xb78a54c6 in Gtk::TreeView::set_cursor () from /usr/lib/libgtkmm-2.0.so.1
(gdb) bt
#0 0xb78a54c6 in Gtk::TreeView::set_cursor () from /usr/lib/libgtkmm-2.0.so.1
#1 0x080b4240 in MQResultSetView::PopupTreeView::on_button_press_event ()
#2 0xb78aeb80 in Gtk::Widget_Class::button_press_event_callback ()
   from /usr/lib/libgtkmm-2.0.so.1
#3 0xb74ffaae in _gtk_marshal_BOOLEAN__BOXED ()
   from /usr/lib/libgtk-x11-2.0.so.0
#4 0xb722a5bf in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
#5 0xb722a351 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#6 0xb723a270 in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
#7 0xb72396ef in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#8 0xb7239b75 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#9 0xb75eedd7 in gtk_widget_send_expose () from /usr/lib/libgtk-x11-2.0.so.0
#10 0xb74fe5c2 in gtk_propagate_event () from /usr/lib/libgtk-x11-2.0.so.0
#11 0xb74fd416 in gtk_main_do_event () from /usr/lib/libgtk-x11-2.0.so.0
#12 0xb73304a5 in _gdk_events_queue () from /usr/lib/libgdk-x11-2.0.so.0
#13 0xb71c1d0f in g_main_depth () from /usr/lib/libglib-2.0.so.0
#14 0xb71c2cb5 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#15 0xb71c2fd7 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#16 0xb71c351e in g_main_loop_run () from /usr/lib/libglib-2.0.so.0
#17 0xb74fccc3 in gtk_main () from /usr/lib/libgtk-x11-2.0.so.0
#18 0xb78571db in Gtk::Main::run_impl () from /usr/lib/libgtkmm-2.0.so.1
#19 0xb7856fc6 in Gtk::Main::run () from /usr/lib/libgtkmm-2.0.so.1
#20 0x0809eeed in main ()