Add support for full asynchronous graphics toolkit running in a separate thread. Add uicontrol and uipanel implementation. * oct-mutex.h (octave_base_mutex::try_lock): New method. (octave_mutex::try_lock): Likewise. (octave_auto_lock::octave_auto_lock): New argument for blocking/non-blocking locks. (octave_auto_lock::ok): New method to test locking state. (octave_auto_lock::operator bool): Likewise. (octave_thread): New utility class. * oct-mutex.cc (octave_base_mutex::try_lock): New method. (octave_w32_mutex::try_lock): Implement it for Win32. (octave_pthread_mutex::try_lock): Implement it for pthread. (octave_thread): Implement new utility class. * octave.cc (octave_main): Initialize octave_thread. * genprops.awk (emit_get_string_array): New function. (emit_declarations): Use it for string_array_property. * graphics.h.in (base_property::set): New argument to control toolkit notifying. (property::set): Likewise. (string_array_property::string_vector_value): New method. (radio_property::do_set): Add warning about abbreviated radio values. (base_graphics_toolkit::initialize): Returns bool. (graphics_toolkit::initialize): Likewise. (base_graphics_object::toolkit_flag): New member. (base_graphics_object::base_graphics_object): Initialize it. (base_graphics_object::valid_toolkit_object): New method. (base_graphics_object::initialize, base_graphics_object::finalize, base_graphics_object::update): Likewise. (graphics_object::initialize, graphics_object::finalize, graphics_object::update): Likewise. (figure::properties::set_toolkit): Move implementation to source file. (base_properties::get_boundingbox): Add parent size argument for optimization. (figure::properties::get_boundingbox): Likewise. (axes::properties::get_boundingbox): Likewise. (figure::properties::map_from_boundingbox): New utility method. (figure::properties::map_to_boundingbox): Likewise. (axes::properties::get_fontsize_points): New utility method. (text::properties::get_fontsize_points): Likewise. (axes::properties::xlabel, axes::properties::ylabel, axes::properties::zlabel, axes::properties::title): Don't notify toolkit on initialization. (axes::initialize): New method override. (uicontrol): New class. (uipanel): Likewise. (graphics_event::create_callback_event): New static method overload. (graphics_event::create_set_event): New argument to prevent circular behavior when property change is triggered from the toolkit. (gh_manager::post_set): Likewise. (gh_manager::do_post_set): Likewise. (gh_manager::make_graphics_handle): New argument controlling toolkit notify. (gh_manager::make_figure_handle): Likewise. (gh_manager::do_make_graphics_handle): Likewise. (gh_manager::do_make_figure_handle): Likewise. (gh_manager::try_lock): New static method. (gh_manager::execute_listener): Likewise. (gh_manager::enable_event_processing): Likewise. (gh_manager::do_try_lock): New method. (gh_manager::do_execute_listener): Likewise. (gh_manager::do_enable_event_processing): Likewise. (gh_manager::event_processing): New member. (gh_manager::execute_callback): Protect graphics_object access. (gh_manager::auto_lock): Inherits from octave_autolock. Renamed from autolock. (gh_manager::auto_lock::auto_lock): New blocking/non-blocking argument. * graphics.cc (default_control_position, default_control_sliderstep, default_panel_position): New utility functions. (convert_font_size): New utility function. (convert_position): Support 2D-only positions. (lookup_object_name): Support uicontrol and uipanel. (make_graphics_object_from_type): Likewise. (root_figure::init_factory_properties): Likewise. (property_list::set, property_list::lookup): Likewise. (base_property::set): New argument controlling toolkit notifying. (base_property::run_listeners): Call gh_manager::execute_listener, allowing to set a property from another thread and run listeners synchronously with octave. (color_property::do_set): Add warning about abbreviated radio value. (double_radio_property::do_set): Likewise. (finalize_r, initialize_r, xinitialize): New utility functions. (gh_manager::do_free): Calls graphics_object::finalize. (base_graphics_toolkit::initialize): Returns bool. (gnuplot_toolkit::initialize): Likewise. (figure::properties::set_toolkit): Move implementation from header. (figure::properties::get_boundingbox): New argument for parent size. (axes::properties::get_boundingbox): Likewise. (figure::properties::map_from_boundingbox): New utility method. (figure::properties::map_to_boundingbox): Likewise. (axes::properties::update_fontunits): Use convert_font_size. (axes::properties::get_fontsize_points): New utility method. (text::properties::get_fontsize_points): Likewise. (axes::initialize): New method override to trigger initialization of labels and title. (uicontrol): New class. (uipanel): Likewise. (gh_manager::gh_manager): Initialize new event_processing member. (gh_manager::do_make_graphics_handle): New argument controlling toolkit notifying. (gh_manager::do_make_figure_handle): Likewise. (callback_event::callback): New member. (callback_event::callback_event): Initialize it. (callback_event::execute): Use it. (set_event::notify_toolkit): New member. (set_event::set_event): Initialize it. (set_event::execute): Use it. Also allow to set read-only properties. (graphics_event::create_callback_event): New static method overload. (graphics_event::create_set_event): New argument controlling toolkit notifying. (gh_manager::do_restore_gcbo): Rename autolock to auto_lock. (gh_manager::do_post_callback, gh_manager::do_post_function): Likewise. (Fishandle, Fset, Fget, F__get__): Likewise. (F__go_figure__, F__calc_dimensions__, GO_BODY): Likewise. (F__go_delete__, F__go_axes_init__, F__go_handles__, F__go_figure_handles__, Favailable_graphics_toolkits, Faddlistener, Fdellistener, Faddproperty): Likewise. (get_property_from_handle, set_property_in_handle): Likewise. (gh_manager::do_post_set): Likewise. New argument controlling toolkit notifying. (gh_manager::do_execute_listener): New method. (gh_manager::do_enable_event_processing): Likewise. (gh_manager::do_execute_callback): Check callback argument validity. Rename autolock to auto_lock. (gh_manager::do_process_events): Execute drawnow at the end of event processing loop, avoiding recursivity. Maintain the input event hook if gh_manager::event_processing is non zero. (make_graphics_object): Postpone object's toolkit initialization at the end of the object creation. (F__go_figure__): Likewise. (F__go_uicontrol__, F__go_uipanel__): New functions. * __init_fltk__.cc (fltk_graphics_toolkit::initialise): New method. * gl-render.h (opengl_renderer::draw): New argument to identify top-level calls. (opengl_renderer::draw_uipanel): New method. (opengl_renderer::init_gl_context): Likewise. * gl-render.cc (opengl_renderer::draw): New argument to identify top-level calls. Skip uicontrol objects. Handle uipanel objects when top-level. (opengl_renderer::init_gl_context): New method. (opengl_renderer::draw_figure): Use it. (opengl_renderer::draw_uipanel): New method.