After closing multiple pasted images Pinta crashes

This bug looks like regression (I can't reproduce it on Pinta 0.5 on Ubuntu 10.10).

Pinta 0.6 on Windows XP sp3
1. <Print Screen> and paste the picture with <Alt>+V
2. From toolbar select New button accept default windows size and OK button.
3. Menu Window | Close all

Error is returned:
Unhandled exception:
Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

Details:
System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
   at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
   at System.ThrowHelper.ThrowArgumentOutOfRangeException()
   at System.Collections.Generic.List`1.get_Item(Int32 index)
   at Pinta.Core.WorkspaceManager.get_ActiveWorkspace() in c:\Users\Jonathan\Documents\Visual Studio 2010\Projects\Pinta\Pinta.Core\Managers\WorkspaceManager.cs:line 58
   at Pinta.Core.WorkspaceManager.get_Scale() in c:\Users\Jonathan\Documents\Visual Studio 2010\Projects\Pinta\Pinta.Core\Managers\WorkspaceManager.cs:line 79
   at Pinta.Gui.Widgets.PintaCanvas.OnExposeEvent(EventExpose e) in c:\Users\Jonathan\Documents\Visual Studio 2010\Projects\Pinta\Pinta.Gui.Widgets\Widgets\Canvas\PintaCanvas.cs:line 97
   at Gtk.Widget.exposeevent_cb(IntPtr widget, IntPtr evnt)