[gnome-panel] toplevel: fix -Wimplicit-fallthrough warning

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 788ee8a8a0ff815e0fe64869db11124098a2c1af
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Feb 16 12:03:00 2020 +0200

    toplevel: fix -Wimplicit-fallthrough warning

 gnome-panel/panel-toplevel.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/gnome-panel/panel-toplevel.c b/gnome-panel/panel-toplevel.c
index 0c4dd3f18..3c5dcbc0d 100644
--- a/gnome-panel/panel-toplevel.c
+++ b/gnome-panel/panel-toplevel.c
@@ -1144,13 +1144,16 @@ panel_toplevel_handle_grab_op_key_event (PanelToplevel *toplevel,
                break;
        case GDK_KEY_Escape:
                panel_toplevel_cancel_grab_op (toplevel, event->time);
-       case GDK_KEY_Return: /* drop through*/
+               panel_toplevel_end_grab_op (toplevel, event->time);
+               retval = TRUE;
+               break;
+       case GDK_KEY_Return:
        case GDK_KEY_KP_Enter:
        case GDK_KEY_space:
        case GDK_KEY_KP_Space:
+       default:
                panel_toplevel_end_grab_op (toplevel, event->time);
                retval = TRUE;
-       default: /* drop through*/
                break;
        }