UI Definitions

The UI definitions are specified in an XML format which can be roughly described by the following DTD.

<!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     EMPTY >
<!ELEMENT separator    EMPTY >
<!ELEMENT accelerator  EMPTY >
<!ATTLIST menubar      name               #IMPLIED >
<!ATTLIST toolbar      name               #IMPLIED >
<!ATTLIST popup        name               #IMPLIED >
<!ATTLIST placeholder  name               #IMPLIED >
<!ATTLIST menu         name               #IMPLIED
                       action             #REQUIRED
                       position (top|bot) #IMPLIED >
<!ATTLIST menuitem     name               #IMPLIED
                       action             #REQUIRED
                       position (top|bot) #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 ancestry and every menuitem must have a menubar or popup in its ancestry. Since a GMarkup parser is used to parse the UI description, it must not only be valid XML, but valid GMarkup. If a name is not specified, it defaults to the action. If an action is not specified either, the element name is used.

<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:

The "position" attribute determines where a constructed widget is positioned with respect to its siblings in the partially constructed tree. If it is "top", the widget is prepended, otherwise it is appended.

UI Merging

The most remarkable feature of gtk.UIManager is that it can overlay a set of menuitems and toolitems over another one, and demerge them later.

Merging is done based on the name of the XML elements. Each element is identified by a path which consists of the names of its ancestors, 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

The separators created by gtk.UIManager 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.

Empty Menus

Submenus pose similar problems to separators in connection with merging. It is impossible to know in advance whether they will end up empty after merging. gtk.UIManager offers two ways to treat empty submenus:

The behavior is chosen based on the "is_important" property of the action to which the submenu is associated.

gtk.UIManager.set_add_tearoffs

    def set_add_tearoffs(add_tearoffs)

The add_tearoffs() method sets the "add_tearoffs" property to the value of add_tearoffs. If add_tearoffs is TRUE regular menus generated by this gtk.UIManager will have tearoff menu items.

Note that this only affects regular menus. Generated popup menus never have tearoff menu items.

gtk.UIManager.get_add_tearoffs

    def get_add_tearoffs()

The get_add_tearoffs() method returns the value of the "add-tearoffs" property. If "add-tearoffs" is TRUE regular menus generated will have tearoff menu items.

gtk.UIManager.insert_action_group

    def insert_action_group(action_group, pos)

The insert_action_group() method inserts the gtk.ActionGroup specified by action_group into the list of associated action groups at the position specified by pos. Actions in earlier groups hide actions with the same name in later groups.

gtk.UIManager.remove_action_group

    def remove_action_group(action_group)

The remove_action_group() method removes the gtk.ActionGroup specified by action_group from the list of associated action groups.

gtk.UIManager.get_action_groups

    def get_action_groups()

The get_action_groups() method returns the list of associated gtk.ActionGroup objects.

gtk.UIManager.get_accel_group

    def get_accel_group()

The get_accel_group() method returns the associated gtk.AccelGroup.

gtk.UIManager.get_widget

    def get_widget(path)

The get_widget() method looks up a widget by following the path specified by path. The path consists of the names specified in the XML description of the UI. separated by '/'. Elements that 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.

gtk.UIManager.get_toplevels

    def get_toplevels(types)

The get_toplevels() method returns a list of all toplevel widgets of the types specified by types.

gtk.UIManager.get_action

    def get_action(path)

The get_action() method looks up a gtk.Action by following a path. See the get_widget() method for more information about paths.

gtk.UIManager.add_ui_from_string

    def add_ui_from_string(buffer)

The add_ui_from_string() method parses the string specified by buffer that contains a UI definition and merges it with the current contents of the ui manager. An enclosing <ui> element is added if it is missing.

This method raise the GError exception if an error occurs during the parsing of the string.

gtk.UIManager.add_ui_from_file

    def add_ui_from_file(filename)

The add_ui_from_file() method parses the file specified by filename that contains a UI definition and merges it with the current contents of the ui manager.

This method raise the GError exception if an error occurs during the parsing of the file.

gtk.UIManager.add_ui

    def add_ui(merge_id, path, name, action, type, top)

The add_ui() method adds a UI element of the type specified by type to the current contents of the ui manager at the location specified by path. Note that path must not start with "/ui" though "ui" is acceptable. For example "/menubar" or "ui/menubar" is acceptable but "/ui/menubar" is not. type must be one of:

gtk.UIManager.remove_ui

    def remove_ui(merge_id)

The remove_ui() method unmerges the part of the ui manager content identified by merge_id.

gtk.UIManager.get_ui

    def get_ui()

The get_ui() method creates a UI definition of the merged UI.

gtk.UIManager.ensure_update

    def ensure_update()

The ensure_update() method makes sure that all pending updates to the UI have been completed. This may occasionally be necessary, since gtk.UIManager updates the UI in an idle function. A typical example where this method is useful is to enforce that the menubar and toolbar have been added to the main window before showing it:

  window.add(vbox) 
  merge.connect("add_widget", add_widget, vbox)
  merge.add_ui_from_file("my-menus")
  merge.add_ui_from_file("my-toolbars")
  merge.ensure_update()  
  window.show()

gtk.UIManager.new_merge_id

    def new_merge_id()

The new_merge_id() method returns an unused merge id, suitable for use with the add_ui() method. The returned merge ids are monotonically increasing integer values.

The "actions-changed" gtk.UIManager Signal

    def callback(uimanager, user_param1, ...)

The "actions-changed" signal is emitted when the set of actions changes.

The "add-widget" gtk.UIManager Signal

    def callback(uimanager, widget, user_param1, ...)

The "add-widget" signal is emitted for each generated menubar and toolbar. The added widget is specified by widget. It is not emitted for generated popup menus, which can be retrieved by the get_widget() method.

The "connect-proxy" gtk.UIManager Signal

    def callback(uimanager, action, widget, user_param1, ...)

The "connect-proxy" signal is emitted after connecting the proxy widget specified by widget to the gtk.Action specified by 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.

The "disconnect-proxy" gtk.UIManager Signal

    def callback(uimanager, action, widget, user_param1, ...)

The "disconnect-proxy" signal is emitted when widget is disconnected from action.

The "post-activate" gtk.UIManager Signal

    def callback(uimanager, action, user_param1, ...)

The "post-activate" signal is emitted after action is activated. This signal is intended for applications to get notification after any action is activated.

The "pre-activate" gtk.UIManager Signal

    def callback(uimanager, action, user_param1, ...)

The "pre-activate" signal is emitted before action is activated. This signal is intended for applications to get notification before any action is activated.