> GtkUIManager is deprecated since GTK+ 3.10. To construct user interfaces > from XML definitions, you should use Gtk.Builder.Gtk_Builder, Glib.Menu_Model.Gmenu_Model, et al. To > work with actions, use Glib.Action.Gaction, Gtk.Actionable.Gtk_Actionable et al. These newer classes > support richer functionality and integration with various desktop shells. > It should be possible to migrate most/all functionality from GtkUIManager.
A Gtk.UI_Manager.Gtk_UI_Manager constructs a user interface (menus and toolbars) from one or more UI definitions, which reference actions from one or more action groups.
# UI Definitions # {XML-UI}
The UI definitions are specified in an XML format which can be roughly described by the following DTD.
> Do not confuse the GtkUIManager UI Definitions described here with > the similarly named [GtkBuilder UI Definitions][BUILDER-UI].
<!ELEMENT ui (menubar|toolbar|popup|accelerator)* >
<!ELEMENT menubar (menuitem|separator|placeholder|menu)* >
<!ELEMENT menu (menuitem|separator|placeholder|menu)* >
<!ELEMENT popup (menuitem|separator|placeholder|menu)* >
<!ELEMENT toolbar (toolitem|separator|placeholder)* >
<!ELEMENT placeholder (menuitem|toolitem|separator|placeholder|menu)* >
<!ELEMENT menuitem EMPTY >
<!ELEMENT toolitem (menu?) >
<!ELEMENT separator EMPTY >
<!ELEMENT accelerator EMPTY >
<!ATTLIST menubar name IMPLIED
action IMPLIED >
<!ATTLIST toolbar name IMPLIED
action IMPLIED >
<!ATTLIST popup name IMPLIED
action IMPLIED
accelerators (true|false) IMPLIED >
<!ATTLIST placeholder name IMPLIED
action IMPLIED >
<!ATTLIST separator name IMPLIED
action IMPLIED
expand (true|false) IMPLIED >
<!ATTLIST menu name IMPLIED
action REQUIRED
position (top|bot) IMPLIED >
<!ATTLIST menuitem name IMPLIED
action REQUIRED
position (top|bot) IMPLIED
always-show-image (true|false) IMPLIED >
<!ATTLIST toolitem name IMPLIED
action REQUIRED
position (top|bot) IMPLIED >
<!ATTLIST accelerator name IMPLIED
action REQUIRED >
There are some additional restrictions beyond those specified in the DTD, e.g. every toolitem must have a toolbar in its anchestry and every menuitem must have a menubar or popup in its anchestry. Since a GMarkup_Parser is used to parse the UI description, it must not only be valid XML, but valid markup.
If a name is not specified, it defaults to the action. If an action is not specified either, the element name is used. The name and action attributes must not contain "/" characters after parsing (since that would mess up path lookup) and must be usable as XML attributes when enclosed in doublequotes, thus they must not """ characters or references to the " entity.
# A UI definition #
<ui>
<menubar>
<menu name="FileMenu" action="FileMenuAction">
<menuitem name="New" action="New2Action" />
<placeholder name="FileMenuAdditions" />
</menu>
<menu name="JustifyMenu" action="JustifyMenuAction">
<menuitem name="Left" action="justify-left"/>
<menuitem name="Centre" action="justify-center"/>
<menuitem name="Right" action="justify-right"/>
<menuitem name="Fill" action="justify-fill"/>
</menu>
</menubar>
<toolbar action="toolbar1">
<placeholder name="JustifyToolItems">
<separator/>
<toolitem name="Left" action="justify-left"/>
<toolitem name="Centre" action="justify-center"/>
<toolitem name="Right" action="justify-right"/>
<toolitem name="Fill" action="justify-fill"/>
<separator/>
</placeholder>
</toolbar>
</ui>
The constructed widget hierarchy is very similar to the element tree of the XML, with the exception that placeholders are merged into their parents. The correspondence of XML elements to widgets should be almost obvious:
menubar
a Gtk.Menu_Bar.Gtk_Menu_Bar
toolbar
a Gtk.Toolbar.Gtk_Toolbar
popup
a toplevel Gtk.Menu.Gtk_Menu
menu
a Gtk.Menu.Gtk_Menu attached to a menuitem
menuitem
a Gtk.Menu_Item.Gtk_Menu_Item subclass, the exact type depends on the action
toolitem
a Gtk.Tool_Item.Gtk_Tool_Item subclass, the exact type depends on the action. Note that toolitem elements may contain a menu element, but only if their associated action specifies a Gtk.Menu_Tool_Button.Gtk_Menu_Tool_Button as proxy.
separator
a Gtk.Separator_Menu_Item.Gtk_Separator_Menu_Item or Gtk.Separator_Tool_Item.Gtk_Separator_Tool_Item
accelerator
a keyboard accelerator
The "position" attribute determines where a constructed widget is positioned wrt. to its siblings in the partially constructed tree. If it is "top", the widget is prepended, otherwise it is appended.
# UI Merging # {UI-Merging}
The most remarkable feature of Gtk.UI_Manager.Gtk_UI_Manager is that it can overlay a set of menuitems and toolitems over another one, and demerge them later.
Merging is done based on the names of the XML elements. Each element is identified by a path which consists of the names of its anchestors, separated by slashes. For example, the menuitem named "Left" in the example above has the path /ui/menubar/JustifyMenu/Left and the toolitem with the same name has path /ui/toolbar1/JustifyToolItems/Left.
# Accelerators #
Every action has an accelerator path. Accelerators are installed together with menuitem proxies, but they can also be explicitly added with <accelerator> elements in the UI definition. This makes it possible to have accelerators for actions even if they have no visible proxies.
# Smart Separators # {Smart-Separators}
The separators created by Gtk.UI_Manager.Gtk_UI_Manager are "smart", i.e. they do not show up in the UI unless they end up between two visible menu or tool items. Separators which are located at the very beginning or end of the menu or toolbar containing them, or multiple separators next to each other, are hidden. This is a useful feature, since the merging of UI elements from multiple sources can make it hard or impossible to determine in advance whether a separator will end up in such an unfortunate position.
For separators in toolbars, you can set expand="true" to turn them from a small, visible separator to an expanding, invisible one. Toolitems following an expanding separator are effectively right-aligned.
# Empty Menus
Submenus pose similar problems to separators inconnection with merging. It is impossible to know in advance whether they will end up empty after merging. Gtk.UI_Manager.Gtk_UI_Manager offers two ways to treat empty submenus:
make them disappear by hiding the menu item they're attached to
add an insensitive "Empty" item
The behaviour is chosen based on the "hide_if_empty" property of the action to which the submenu is associated.
# GtkUIManager as GtkBuildable # {Gtk.UI_Manager.Gtk_UI_Manager-BUILDER-UI}
The GtkUIManager implementation of the GtkBuildable interface accepts GtkActionGroup objects as <child> elements in UI definitions.
A GtkUIManager UI definition as described above can be embedded in an GtkUIManager <object> element in a GtkBuilder UI definition.
The widgets that are constructed by a GtkUIManager can be embedded in other parts of the constructed user interface with the help of the "constructor" attribute. See the example below.
## An embedded GtkUIManager UI definition
<object class="GtkUIManager" id="uiman">
<child>
<object class="GtkActionGroup" id="actiongroup">
<child>
<object class="GtkAction" id="file">
<property name="label">_File</property>
</object>
</child>
</object>
</child>
<ui>
<menubar name="menubar1">
<menu action="file">
</menu>
</menubar>
</ui>
</object>
<object class="GtkWindow" id="main-window">
<child>
<object class="GtkMenuBar" id="menubar1" constructor="uiman"/>
</child>
</object>
function "+"
(Widget : access Gtk_UI_Manager_Record'Class)
return Gtk.Buildable.Gtk_Buildable
function "-"
(Interf : Gtk.Buildable.Gtk_Buildable)
return Gtk_UI_Manager
Add_Tearoffs_Property : constant Glib.Properties.Property_Boolean;
The "add-tearoffs" property controls whether generated menus have tearoff menu items.
Note that this only affects regular menus. Generated popup menus never have tearoff menu items.
procedure Add_UI
(Self : not null access Gtk_UI_Manager_Record;
Merge_Id : Guint;
Path : UTF8_String;
Name : UTF8_String;
Action : UTF8_String := "";
The_Type : Manager_Item_Type := Manager_Auto;
Top : Boolean := False)
Adds a UI element to the current contents of Manager. If Type is Gtk.UI_Manager.Manager_Auto, GTK+ inserts a menuitem, toolitem or separator if such an element can be inserted at the place determined by Path. Otherwise Type must indicate an element that can be inserted at the place determined by Path. If Path points to a menuitem or toolitem, the new element will be inserted before or after this item, depending on Top. Since: gtk+ 2.4 Deprecated since 3.10, 1
the merge id for the merged UI, see Gtk.UI_Manager.New_Merge_Id
a path
the name for the added UI element
the name of the action to be proxied, or null to add a separator
the type of UI element to add.
if True, the UI element is added before its siblings, otherwise it is added after its siblings.
function Add_UI_From_File
(Self : not null access Gtk_UI_Manager_Record;
Filename : UTF8_String) return Guint
Parses a file containing a [UI definition][XML-UI] and merges it with the current contents of Manager. Since: gtk+ 2.4 Deprecated since 3.10, 1
the name of the file to parse
The merge id for the merged UI. The merge id can be used to unmerge the UI with Gtk.UI_Manager.Remove_UI. If an error occurred, the return value is 0.
function Add_UI_From_Resource
(Self : not null access Gtk_UI_Manager_Record;
Resource_Path : UTF8_String) return Guint
Parses a resource file containing a [UI definition][XML-UI] and merges it with the current contents of Manager. Since: gtk+ 3.4 Deprecated since 3.10, 1
the resource path of the file to parse
The merge id for the merged UI. The merge id can be used to unmerge the UI with Gtk.UI_Manager.Remove_UI. If an error occurred, the return value is 0.
function Add_UI_From_String
(Self : not null access Gtk_UI_Manager_Record;
Buffer : UTF8_String;
Error : access Glib.Error.GError) return Guint
Parses a string containing a [UI definition][XML-UI] and merges it with the current contents of Manager. An enclosing <ui> element is added if it is missing. Since: gtk+ 2.4 Deprecated since 3.10, 1
the string to parse
The merge id for the merged UI. The merge id can be used to unmerge the UI with Gtk.UI_Manager.Remove_UI. If an error occurred, the return value is 0.
type Cb_GObject_Gtk_Action_Gtk_Widget_Void is not null access procedure
(Self : access Glib.Object.GObject_Record'Class;
Action : not null access Gtk.Action.Gtk_Action_Record'Class;
Proxy : not null access Gtk.Widget.Gtk_Widget_Record'Class);
type Cb_GObject_Gtk_Action_Void is not null access procedure
(Self : access Glib.Object.GObject_Record'Class;
Action : not null access Gtk.Action.Gtk_Action_Record'Class);
type Cb_GObject_Gtk_Widget_Void is not null access procedure
(Self : access Glib.Object.GObject_Record'Class;
Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class);
type Cb_GObject_Void is not null access procedure
(Self : access Glib.Object.GObject_Record'Class);
type Cb_Gtk_UI_Manager_Gtk_Action_Gtk_Widget_Void is not null access procedure
(Self : access Gtk_UI_Manager_Record'Class;
Action : not null access Gtk.Action.Gtk_Action_Record'Class;
Proxy : not null access Gtk.Widget.Gtk_Widget_Record'Class);
type Cb_Gtk_UI_Manager_Gtk_Action_Void is not null access procedure
(Self : access Gtk_UI_Manager_Record'Class;
Action : not null access Gtk.Action.Gtk_Action_Record'Class);
type Cb_Gtk_UI_Manager_Gtk_Widget_Void is not null access procedure
(Self : access Gtk_UI_Manager_Record'Class;
Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class);
type Cb_Gtk_UI_Manager_Void is not null access procedure (Self : access Gtk_UI_Manager_Record'Class);
procedure Ensure_Update (Self : not null access Gtk_UI_Manager_Record)
Makes sure that all pending updates to the UI have been completed. This may occasionally be necessary, since Gtk.UI_Manager.Gtk_UI_Manager updates the UI in an idle function. A typical example where this function is useful is to enforce that the menubar and toolbar have been added to the main window before showing it:
gtk_container_add (GTK_CONTAINER (window), vbox);
g_signal_connect (merge, "add-widget",
G_CALLBACK (add_widget), vbox);
gtk_ui_manager_add_ui_from_file (merge, "my-menus");
gtk_ui_manager_add_ui_from_file (merge, "my-toolbars");
gtk_ui_manager_ensure_update (merge);
gtk_widget_show (window);
Since: gtk+ 2.4 Deprecated since 3.10, 1
function Get_Accel_Group
(Self : not null access Gtk_UI_Manager_Record)
return Gtk.Accel_Group.Gtk_Accel_Group
Returns the Gtk.Accel_Group.Gtk_Accel_Group associated with Manager. Since: gtk+ 2.4 Deprecated since 3.10, 1
the Gtk.Accel_Group.Gtk_Accel_Group.
function Get_Action
(Self : not null access Gtk_UI_Manager_Record;
Path : UTF8_String) return Gtk.Action.Gtk_Action
Looks up an action by following a path. See Gtk.UI_Manager.Get_Widget for more information about paths. Since: gtk+ 2.4 Deprecated since 3.10, 1
a path
the action whose proxy widget is found by following the path, or null if no widget was found.
function Get_Action_Groups
(Self : not null access Gtk_UI_Manager_Record)
return Glib.Object.Object_Simple_List.Glist
Returns the list of action groups associated with Manager. Since: gtk+ 2.4 Deprecated since 3.10, 1
function Get_Add_Tearoffs
(Self : not null access Gtk_UI_Manager_Record) return Boolean
Returns whether menus generated by this Gtk.UI_Manager.Gtk_UI_Manager will have tearoff menu items. Since: gtk+ 2.4 Deprecated since 3.4, 1
whether tearoff menu items are added
function Get_Toplevels
(Self : not null access Gtk_UI_Manager_Record;
Types : Manager_Item_Type) return Gtk.Widget.Widget_SList.GSlist
Obtains a list of all toplevel widgets of the requested types. Since: gtk+ 2.4 Deprecated since 3.10, 1
specifies the types of toplevel widgets to include. Allowed types are GTK_UI_MANAGER_MENUBAR, GTK_UI_MANAGER_TOOLBAR and GTK_UI_MANAGER_POPUP.
function Get_Type return Glib.GType
function Get_Ui
(Self : not null access Gtk_UI_Manager_Record) return UTF8_String
Creates a [UI definition][XML-UI] of the merged UI. Since: gtk+ 2.4 Deprecated since 3.10, 1
A newly allocated string containing an XML representation of the merged UI.
function Get_Widget
(Self : not null access Gtk_UI_Manager_Record;
Path : UTF8_String) return Gtk.Widget.Gtk_Widget
Looks up a widget by following a path. The path consists of the names specified in the XML description of the UI. separated by "/". Elements which don't have a name or action attribute in the XML (e.g. <popup>) can be addressed by their XML element name (e.g. "popup"). The root element ("/ui") can be omitted in the path. Note that the widget found by following a path that ends in a <menu>; element is the menuitem to which the menu is attached, not the menu it manages. Also note that the widgets constructed by a ui manager are not tied to the lifecycle of the ui manager. If you add the widgets returned by this function to some container or explicitly ref them, they will survive the destruction of the ui manager. Since: gtk+ 2.4 Deprecated since 3.10, 1
a path
the widget found by following the path, or null if no widget was found
procedure Gtk_New (Self : out Gtk_UI_Manager)
Creates a new ui manager object. Since: gtk+ 2.4 Initialize does nothing if the object was already created with another call to Initialize* or G_New.
type Gtk_UI_Manager is access all Gtk_UI_Manager_Record'Class;
function Gtk_UI_Manager_New return Gtk_UI_Manager
Creates a new ui manager object. Since: gtk+ 2.4
type Gtk_UI_Manager_Record is new GObject_Record with null record;
package Implements_Gtk_Buildable is new Glib.Types.Implements
(Gtk.Buildable.Gtk_Buildable, Gtk_UI_Manager_Record, Gtk_UI_Manager);
procedure Initialize (Self : not null access Gtk_UI_Manager_Record'Class)
Creates a new ui manager object. Since: gtk+ 2.4 Initialize does nothing if the object was already created with another call to Initialize* or G_New.
procedure Insert_Action_Group
(Self : not null access Gtk_UI_Manager_Record;
Action_Group : not null access Gtk.Action_Group.Gtk_Action_Group_Record'Class;
Pos : Glib.Gint)
Inserts an action group into the list of action groups associated with Manager. Actions in earlier groups hide actions with the same name in later groups. If Pos is larger than the number of action groups in Manager, or negative, Action_Group will be inserted at the end of the internal list. Since: gtk+ 2.4 Deprecated since 3.10, 1
the action group to be inserted
the position at which the group will be inserted.
Manager_Accelerator : constant Manager_Item_Type := 256;
Manager_Auto : constant Manager_Item_Type := 0;
type Manager_Item_Type is mod 2 ** Integer'Size;
These enumeration values are used by Gtk.UI_Manager.Add_UI to determine what UI element to create.
package Manager_Item_Type_Properties is
new Generic_Internal_Discrete_Property (Manager_Item_Type);
Manager_Menu : constant Manager_Item_Type := 2;
Manager_Menubar : constant Manager_Item_Type := 1;
Manager_Menuitem : constant Manager_Item_Type := 32;
Manager_Placeholder : constant Manager_Item_Type := 8;
Manager_Popup : constant Manager_Item_Type := 16;
Manager_Popup_With_Accels : constant Manager_Item_Type := 512;
Manager_Separator : constant Manager_Item_Type := 128;
Manager_Toolbar : constant Manager_Item_Type := 4;
Manager_Toolitem : constant Manager_Item_Type := 64;
function New_Merge_Id
(Self : not null access Gtk_UI_Manager_Record) return Guint
Returns an unused merge id, suitable for use with Gtk.UI_Manager.Add_UI. Since: gtk+ 2.4 Deprecated since 3.10, 1
an unused merge id.
procedure On_Actions_Changed
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_GObject_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
The ::actions-changed signal is emitted whenever the set of actions changes.
procedure On_Actions_Changed
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_Gtk_UI_Manager_Void;
After : Boolean := False)
The ::actions-changed signal is emitted whenever the set of actions changes.
procedure On_Add_Widget
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_GObject_Gtk_Widget_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
The ::add-widget signal is emitted for each generated menubar and toolbar. It is not emitted for generated popup menus, which can be obtained by Gtk.UI_Manager.Get_Widget.
procedure On_Add_Widget
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_Gtk_UI_Manager_Gtk_Widget_Void;
After : Boolean := False)
The ::add-widget signal is emitted for each generated menubar and toolbar. It is not emitted for generated popup menus, which can be obtained by Gtk.UI_Manager.Get_Widget.
procedure On_Connect_Proxy
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_GObject_Gtk_Action_Gtk_Widget_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
The ::connect-proxy signal is emitted after connecting a proxy to an action in the group.
This is intended for simple customizations for which a custom action class would be too clumsy, e.g. showing tooltips for menuitems in the statusbar.
Callback parameters: -- @param Action the action -- @param Proxy the proxy
procedure On_Connect_Proxy
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_Gtk_UI_Manager_Gtk_Action_Gtk_Widget_Void;
After : Boolean := False)
The ::connect-proxy signal is emitted after connecting a proxy to an action in the group.
This is intended for simple customizations for which a custom action class would be too clumsy, e.g. showing tooltips for menuitems in the statusbar.
Callback parameters: -- @param Action the action -- @param Proxy the proxy
procedure On_Disconnect_Proxy
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_GObject_Gtk_Action_Gtk_Widget_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
The ::disconnect-proxy signal is emitted after disconnecting a proxy from an action in the group.
Callback parameters: -- @param Action the action -- @param Proxy the proxy
procedure On_Disconnect_Proxy
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_Gtk_UI_Manager_Gtk_Action_Gtk_Widget_Void;
After : Boolean := False)
The ::disconnect-proxy signal is emitted after disconnecting a proxy from an action in the group.
Callback parameters: -- @param Action the action -- @param Proxy the proxy
procedure On_Post_Activate
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_GObject_Gtk_Action_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
The ::post-activate signal is emitted just after the Action is activated.
This is intended for applications to get notification just after any action is activated.
procedure On_Post_Activate
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_Gtk_UI_Manager_Gtk_Action_Void;
After : Boolean := False)
The ::post-activate signal is emitted just after the Action is activated.
This is intended for applications to get notification just after any action is activated.
procedure On_Pre_Activate
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_GObject_Gtk_Action_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
The ::pre-activate signal is emitted just before the Action is activated.
This is intended for applications to get notification just before any action is activated.
procedure On_Pre_Activate
(Self : not null access Gtk_UI_Manager_Record;
Call : Cb_Gtk_UI_Manager_Gtk_Action_Void;
After : Boolean := False)
The ::pre-activate signal is emitted just before the Action is activated.
This is intended for applications to get notification just before any action is activated.
type Property_Manager_Item_Type is new Manager_Item_Type_Properties.Property;
procedure Remove_Action_Group
(Self : not null access Gtk_UI_Manager_Record;
Action_Group : not null access Gtk.Action_Group.Gtk_Action_Group_Record'Class)
Removes an action group from the list of action groups associated with Manager. Since: gtk+ 2.4 Deprecated since 3.10, 1
the action group to be removed
procedure Remove_UI
(Self : not null access Gtk_UI_Manager_Record;
Merge_Id : Guint)
Unmerges the part of Manager's content identified by Merge_Id. Since: gtk+ 2.4 Deprecated since 3.10, 1
a merge id as returned by Gtk.UI_Manager.Add_UI_From_String
procedure Set_Add_Tearoffs
(Self : not null access Gtk_UI_Manager_Record;
Add_Tearoffs : Boolean)
Sets the "add_tearoffs" property, which controls whether menus generated by this Gtk.UI_Manager.Gtk_UI_Manager will have tearoff menu items. Note that this only affects regular menus. Generated popup menus never have tearoff menu items. Since: gtk+ 2.4 Deprecated since 3.4, 1
whether tearoff menu items are added
Signal_Actions_Changed : constant Glib.Signal_Name := "actions-changed";
The ::actions-changed signal is emitted whenever the set of actions changes.
Signal_Add_Widget : constant Glib.Signal_Name := "add-widget";
The ::add-widget signal is emitted for each generated menubar and toolbar. It is not emitted for generated popup menus, which can be obtained by Gtk.UI_Manager.Get_Widget.
Signal_Connect_Proxy : constant Glib.Signal_Name := "connect-proxy";
The ::connect-proxy signal is emitted after connecting a proxy to an action in the group.
This is intended for simple customizations for which a custom action class would be too clumsy, e.g. showing tooltips for menuitems in the statusbar.
Callback parameters: -- @param Action the action -- @param Proxy the proxy
Signal_Disconnect_Proxy : constant Glib.Signal_Name := "disconnect-proxy";
The ::disconnect-proxy signal is emitted after disconnecting a proxy from an action in the group.
Callback parameters: -- @param Action the action -- @param Proxy the proxy
Signal_Post_Activate : constant Glib.Signal_Name := "post-activate";
The ::post-activate signal is emitted just after the Action is activated.
This is intended for applications to get notification just after any action is activated.
Signal_Pre_Activate : constant Glib.Signal_Name := "pre-activate";
The ::pre-activate signal is emitted just before the Action is activated.
This is intended for applications to get notification just before any action is activated.
Ui_Property : constant Glib.Properties.Property_String;