Additionally, performing a "select all" from the Edit menu after clicking undo twice causes Pinta to crash. here's the stacktrace:

Stacktrace:

  at (wrapper managed-to-native) Cairo.NativeMethods.cairo_image_surface_get_width (intptr) <0x00004>
  at (wrapper managed-to-native) Cairo.NativeMethods.cairo_image_surface_get_width (intptr) <0xffffffff>
  at Cairo.ImageSurface.get_Width () <0x00014>
  at Pinta.CellRendererSurface.RenderCell (Cairo.Context,int,int) <0x00044>
  at Pinta.CellRendererSurface.Render (Gdk.Drawable,Gtk.Widget,Gdk.Rectangle,Gdk.Rectangle,Gdk.Rectangle,Gtk.CellRendererState) <0x000c6>
  at Gtk.CellRenderer.Render_cb (intptr,intptr,intptr,Gdk.Rectangle&,Gdk.Rectangle&,Gdk.Rectangle&,Gtk.CellRendererState) <0x00179>
  at (wrapper native-to-managed) Gtk.CellRenderer.Render_cb (intptr,intptr,intptr,Gdk.Rectangle&,Gdk.Rectangle&,Gdk.Rectangle&,Gtk.CellRendererState) <0xffffffff>
  at (wrapper managed-to-native) Gtk.Application.gtk_main () <0x00004>
  at (wrapper managed-to-native) Gtk.Application.gtk_main () <0xffffffff>
  at Gtk.Application.Run () <0x0000a>
  at Pinta.MainClass.Main (string[]) <0x002a8>
  at (wrapper runtime-invoke) Pinta.MainClass.runtime_invoke_void_object (object,intptr,intptr,intptr) <0xffffffff>

Native stacktrace:

	/usr/bin/cli() [0x80ca6e4]
	/usr/bin/cli() [0x80f6893]
	[0x404410]
	[0x3fef6a5]
	[0x3fef665]
	[0x3fef245]
	[0x3feeff7]
	[0x3feeef2]
	[0xf1e92e]
	/usr/lib/libgtk-x11-2.0.so.0(gtk_cell_renderer_render+0xc0) [0x90dab80]
	/usr/lib/libgtk-x11-2.0.so.0(+0x288db6) [0x92d3db6]
	/usr/lib/libgtk-x11-2.0.so.0(+0x289bc4) [0x92d4bc4]
	/usr/lib/libgtk-x11-2.0.so.0(+0x284459) [0x92cf459]
	/usr/lib/libgtk-x11-2.0.so.0(+0x28546a) [0x92d046a]
	/usr/lib/libgtk-x11-2.0.so.0(+0x155e58) [0x91a0e58]
	/usr/lib/libgobject-2.0.so.0(+0xb817) [0xaab817]
	/usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x19a) [0xaad1aa]
	/usr/lib/libgobject-2.0.so.0(+0x24d76) [0xac4d76]
	/usr/lib/libgobject-2.0.so.0(g_signal_emit_valist+0x603) [0xac6613]
	/usr/lib/libgobject-2.0.so.0(g_signal_emit+0x32) [0xac6f02]
	/usr/lib/libgtk-x11-2.0.so.0(+0x29c5c6) [0x92e75c6]
	/usr/lib/libgtk-x11-2.0.so.0(gtk_main_do_event+0x65b) [0x9199abb]
	/usr/lib/libgdk-x11-2.0.so.0(+0x3e43b) [0x86b43b]
	/usr/lib/libgdk-x11-2.0.so.0(+0x3e3ea) [0x86b3ea]
	/usr/lib/libgdk-x11-2.0.so.0(+0x3e3ea) [0x86b3ea]
	/usr/lib/libgdk-x11-2.0.so.0(+0x6e214) [0x89b214]
	/usr/lib/libgdk-x11-2.0.so.0(+0x3abb4) [0x867bb4]
	/usr/lib/libgdk-x11-2.0.so.0(gdk_window_process_all_updates+0x157) [0x86cb17]
	/usr/lib/libgtk-x11-2.0.so.0(+0xb5d6d) [0x9100d6d]
	/usr/lib/libgdk-x11-2.0.so.0(+0x16f08) [0x843f08]
	/lib/libglib-2.0.so.0(+0x3a0b1) [0x14a0b1]
	/lib/libglib-2.0.so.0(g_main_context_dispatch+0x1d5) [0x14c0c5]
	/lib/libglib-2.0.so.0(+0x3fed8) [0x14fed8]
	/lib/libglib-2.0.so.0(g_main_loop_run+0x187) [0x150417]
	/usr/lib/libgtk-x11-2.0.so.0(gtk_main+0xb9) [0x9199d69]
	[0x3fecd70]
	[0x3fecd33]
	[0x427559]
	[0x427204]
	/usr/bin/cli(mono_runtime_exec_main+0xde) [0x8113b1e]
	/usr/bin/cli(mono_runtime_run_main+0x15a) [0x811429a]
	/usr/bin/cli(mono_main+0x18c4) [0x80b3524]
	/usr/bin/cli() [0x805ad25]
	/lib/libc.so.6(__libc_start_main+0xe6) [0x1f1ce6]
	/usr/bin/cli() [0x805ac61]

Debug info from gdb:

Could not attach to process.  If your uid matches the uid of the target
process, check the setting of /proc/sys/kernel/ptrace_scope, or try again
as the root user.  For more details, see /etc/sysctl.d/10-ptrace.conf
ptrace: Operation not permitted.

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

Aborted