[rhythmbox] add missing cast from previous commit. oops.

[Jonathan Matthew <jmatthew src gnome org>]

commit e3c653c0236f660247d801415e514a93d80adb2f
Author: Jonathan Matthew <jonathan d14n org>
Date:   Sat Dec 1 20:48:59 2012 +1000

    add missing cast from previous commit.  oops.

 shell/rb-shell.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/shell/rb-shell.c b/shell/rb-shell.c
index 561cce8..57da123 100644
--- a/shell/rb-shell.c
+++ b/shell/rb-shell.c
@@ -697,7 +697,7 @@ construct_widgets (RBShell *shell)
 	shell->priv->bottom_container = GTK_BOX (gtk_box_new (GTK_ORIENTATION_VERTICAL, 0));
 	shell->priv->sidebar_container = GTK_BOX (gtk_box_new (GTK_ORIENTATION_VERTICAL, 0));
 	shell->priv->right_sidebar_container = GTK_BOX (gtk_box_new (GTK_ORIENTATION_VERTICAL, 0));
-	gtk_widget_show (shell->priv->bottom_container);
+	gtk_widget_show (GTK_WIDGET (shell->priv->bottom_container));
 
 	/* set up sidebars */
 	shell->priv->paned = gtk_paned_new (GTK_ORIENTATION_HORIZONTAL);