[gimp] Issue #835: warnings building with Clang.

[Jehan <jehanp src gnome org>]

commit 90bc9e10f14644a2bf6c0071c0762d5f34f0957d
Author: Jehan <jehan girinstud io>
Date:   Tue May 7 18:12:47 2019 +0900

    Issue #835: warnings building with Clang.
    
    Fix one warning and one error (introduced in commit 3bf2a3c1660).

 app/actions/dockable-commands.c | 2 +-
 app/menus/windows-menu.c        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/app/actions/dockable-commands.c b/app/actions/dockable-commands.c
index ec80e40223..75564e00b9 100644
--- a/app/actions/dockable-commands.c
+++ b/app/actions/dockable-commands.c
@@ -191,7 +191,7 @@ dockable_toggle_view_cmd_callback (GtkAction *action,
                       gtk_widget_show (new_dockable);
 
                       gtk_container_remove (GTK_CONTAINER (dockbook),
-                                            dockable);
+                                            GTK_WIDGET (dockable));
 
                       gtk_notebook_set_current_page (GTK_NOTEBOOK (dockbook),
                                                      page_num);
diff --git a/app/menus/windows-menu.c b/app/menus/windows-menu.c
index 28d891a044..5fe057ff2a 100644
--- a/app/menus/windows-menu.c
+++ b/app/menus/windows-menu.c
@@ -416,7 +416,7 @@ windows_menu_display_query_tooltip (GtkWidget  *widget,
   gint       height;
 
   if (! image)
-    return;
+    return FALSE;
 
   text = gtk_widget_get_tooltip_text (widget);
   gtk_tooltip_set_text (tooltip, text);