center layout: Fix handling of expanding center child

We were not taking spacing into account when adjusting
the size of an expanding center child, causing it to slip
under the end child at times.

Fixes: #3506

diff --git a/gtk/gtkcenterlayout.c b/gtk/gtkcenterlayout.c
index f9fa988ca7ef7ab47150dcec2d599b642af4e12e..b2dee1db0d11a2c8cb5f258365275c7a87b5c046 100644 (file)
--- a/gtk/gtkcenterlayout.c
+++ b/gtk/gtkcenterlayout.c
@@ -177,7 +177,7 @@ gtk_center_layout_distribute (GtkCenterLayout  *self,
         center_pos = size - center_size - end_size - spacing;
       else if (center_expand)
         {
-          center_size = size - 2 * MAX (start_size, end_size);
+          center_size = size - 2 * (MAX (start_size, end_size) + spacing);
           center_pos = (size / 2) - (center_size / 2) + spacing;
         }