[gnome-control-center] window: Ensure a constant minimum panel width

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 90dd7651cd9adc9cf0dac9718654f32f4be4dc64
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Wed Nov 28 09:42:49 2018 +0100

    window: Ensure a constant minimum panel width
    
    Ensure all panels take at least 300pt of width to ensure a minimum of
    usability, readability of the panels and consistency of when the shell
    folds itself.

 shell/cc-window.ui | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/shell/cc-window.ui b/shell/cc-window.ui
index b2bcb05ea..3be08f0c1 100644
--- a/shell/cc-window.ui
+++ b/shell/cc-window.ui
@@ -96,6 +96,7 @@
             <property name="hexpand">True</property>
             <property name="vexpand">True</property>
             <property name="transition_type">crossfade</property>
+            <property name="width_request">300</property>
             <style>
               <class name="background"/>
             </style>