[gnome-control-center] color: Use a HdyColumn

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

commit eaeb64d85e3a5551cf5337f5ce53ed4d6ee1d2f4
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Tue Jan 22 00:01:16 2019 +0100

    color: Use a HdyColumn
    
    This helps the panel to fit in narrower windows.

 panels/color/cc-color-panel.ui | 35 +++++++----------------------------
 1 file changed, 7 insertions(+), 28 deletions(-)
---
diff --git a/panels/color/cc-color-panel.ui b/panels/color/cc-color-panel.ui
index 5798d7c05..5f5eac075 100644
--- a/panels/color/cc-color-panel.ui
+++ b/panels/color/cc-color-panel.ui
@@ -762,41 +762,20 @@
         <property name="visible">True</property>
         <property name="can_focus">False</property>
         <child>
-          <object class="GtkBox">
+          <object class="HdyColumn">
             <property name="visible">True</property>
-            <property name="can_focus">False</property>
-
-            <!-- Stub boxes to make the content cover 1/3 of the screen -->
-            <child>
-              <object class="GtkBox">
-                <property name="visible">True</property>
-                <property name="can_focus">False</property>
-                <property name="hexpand">True</property>
-              </object>
-            </child>
-
-            <child>
-              <object class="GtkBox">
-                <property name="visible">True</property>
-                <property name="can_focus">False</property>
-                <property name="hexpand">True</property>
-              </object>
-              <packing>
-                <property name="pack_type">end</property>
-              </packing>
-            </child>
-
-            <!-- Content -->
+            <property name="maximum_width">600</property>
+            <property name="linear_growth_width">400</property>
+            <property name="margin_top">32</property>
+            <property name="margin_bottom">32</property>
+            <property name="margin_start">12</property>
+            <property name="margin_end">12</property>
             <child>
               <object class="GtkBox">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
                 <property name="orientation">vertical</property>
                 <property name="spacing">12</property>
-                <property name="margin_top">32</property>
-                <property name="margin_bottom">32</property>
-                <property name="margin_left">24</property>
-                <property name="margin_right">24</property>
                 <property name="hexpand">True</property>
                 <child>
                   <object class="GtkBox" id="hbox3">