}
+/**
+ * Function to register a hook function for a viewer to show
+ *the content of the viewer.
+ * It will be called by the constructor of the viewer.
+ * @param hook hook function of the viewer.
+ * @param hook_data hook data associated with the hook function.
+ * @param main_win the main window the viewer belongs to.
+ */
+
+void reg_show_viewer(LttvHook hook, gpointer hook_data,
+ MainWindow *main_win)
+{
+ LttvAttributeValue value;
+ LttvHooks * tmp;
+ g_assert(lttv_iattribute_find_by_path(main_win->current_tab->attributes,
+ "hooks/showviewer", LTTV_POINTER, &value));
+ tmp = (LttvHooks*)*(value.v_pointer);
+ if(tmp == NULL){
+ tmp = lttv_hooks_new();
+ *(value.v_pointer) = tmp;
+ }
+ lttv_hooks_add(tmp, hook, hook_data);
+}
+
+
+/**
+ * Function to unregister a viewer's hook function which is used to
+ * show the content of the viewer..
+ * It will be called by the destructor of the viewer.
+ * @param hook hook function of the viewer.
+ * @param hook_data hook data associated with the hook function.
+ * @param main_win the main window the viewer belongs to.
+ */
+
+void unreg_show_viewer(LttvHook hook, gpointer hook_data,
+ MainWindow * main_win)
+{
+ LttvAttributeValue value;
+ LttvHooks * tmp;
+ g_assert(lttv_iattribute_find_by_path(main_win->current_tab->attributes,
+ "hooks/showviewer", LTTV_POINTER, &value));
+ tmp = (LttvHooks*)*(value.v_pointer);
+ if(tmp == NULL) return;
+ lttv_hooks_remove_data(tmp, hook, hook_data);
+}
+
+
+/**
+ * Function to show each viewer in the current tab.
+ * It will be called by main window after it called process_traceset
+ * @param main_win the main window the viewer belongs to.
+ */
+
+void show_viewer(MainWindow *main_win)
+{
+ LttvAttributeValue value;
+ LttvHooks * tmp;
+ g_assert(lttv_iattribute_find_by_path(main_win->current_tab->attributes,
+ "hooks/showviewer", LTTV_POINTER, &value));
+ tmp = (LttvHooks*)*(value.v_pointer);
+ if(tmp == NULL) return;
+ lttv_hooks_call(tmp, NULL);
+}
+
+
/**
* Function to set the focused pane (viewer).
* It will be called by a viewer's signal handle associated with