[gnome-builder/wip/chergert/headerbar] workbench: add sizing workarounds for centering omnibar

[Christian Hergert <chergert src gnome org>]

commit 405a7afdabd3a984280cee823e53279282069ab1
Author: Christian Hergert <chergert redhat com>
Date:   Wed Jun 22 13:41:26 2016 -0700

    workbench: add sizing workarounds for centering omnibar
    
    This is less than ideal, because it's the result of 2 bugs in gtk+ size
    requests that we are working around.
    
    The first, is the lack of hexpand support in left/right of the headerbar.
    The second, is that the center widget + sizing of neighbors is not
    respected when a GtkBox is packed as the custom title.
    
    Where this will be apparent, is when the content is compressed and there
    are uneven buttons on the left/right. You'll see spacing enforced for the
    size group contained widgetry, which will be rather annoying im presume.
    
    Either way, this works for now and allows us to move forward.

 libide/workbench/ide-workbench-header-bar.c  |   16 +++++++----
 libide/workbench/ide-workbench-header-bar.ui |   36 ++++++++++++++++++++++---
 2 files changed, 41 insertions(+), 11 deletions(-)
---
diff --git a/libide/workbench/ide-workbench-header-bar.c b/libide/workbench/ide-workbench-header-bar.c
index ca08781..92d2dc5 100644
--- a/libide/workbench/ide-workbench-header-bar.c
+++ b/libide/workbench/ide-workbench-header-bar.c
@@ -30,6 +30,8 @@ typedef struct
 {
   GtkMenuButton  *menu_button;
   EggPriorityBox *center_box;
+  EggPriorityBox *center_right_box;
+  EggPriorityBox *center_left_box;
   EggPriorityBox *right_box;
   EggPriorityBox *left_box;
 } IdeWorkbenchHeaderBarPrivate;
@@ -53,6 +55,8 @@ ide_workbench_header_bar_class_init (IdeWorkbenchHeaderBarClass *klass)
 
   gtk_widget_class_set_template_from_resource (widget_class, 
"/org/gnome/builder/ui/ide-workbench-header-bar.ui");
   gtk_widget_class_bind_template_child_private (widget_class, IdeWorkbenchHeaderBar, center_box);
+  gtk_widget_class_bind_template_child_private (widget_class, IdeWorkbenchHeaderBar, center_right_box);
+  gtk_widget_class_bind_template_child_private (widget_class, IdeWorkbenchHeaderBar, center_left_box);
   gtk_widget_class_bind_template_child_private (widget_class, IdeWorkbenchHeaderBar, menu_button);
   gtk_widget_class_bind_template_child_private (widget_class, IdeWorkbenchHeaderBar, left_box);
   gtk_widget_class_bind_template_child_private (widget_class, IdeWorkbenchHeaderBar, right_box);
@@ -100,12 +104,12 @@ ide_workbench_header_bar_insert_left (IdeWorkbenchHeaderBar *self,
   /*
    * NOTE: Because GtkHeaderBar does not currently support hexpand, we
    *       need to check the pack_type requested and possibly insert it
-   *       into our custom center-child (with opposite pack_type).
+   *       into our custom center-child.
    */
 
   if (pack_type == GTK_PACK_END)
-    gtk_container_add_with_properties (GTK_CONTAINER (priv->center_box), widget,
-                                       "pack-type", GTK_PACK_START,
+    gtk_container_add_with_properties (GTK_CONTAINER (priv->center_left_box), widget,
+                                       "pack-type", pack_type,
                                        "priority", priority,
                                        NULL);
   else
@@ -130,12 +134,12 @@ ide_workbench_header_bar_insert_right (IdeWorkbenchHeaderBar *self,
   /*
    * NOTE: Because GtkHeaderBar does not currently support hexpand, we
    *       need to check the pack_type requested and possibly insert it
-   *       into our custom center-child (with opposite pack_type).
+   *       into our custom center-child.
    */
 
   if (pack_type == GTK_PACK_START)
-    gtk_container_add_with_properties (GTK_CONTAINER (priv->center_box), widget,
-                                       "pack-type", GTK_PACK_END,
+    gtk_container_add_with_properties (GTK_CONTAINER (priv->center_right_box), widget,
+                                       "pack-type", pack_type,
                                        "priority", priority,
                                        NULL);
   else
diff --git a/libide/workbench/ide-workbench-header-bar.ui b/libide/workbench/ide-workbench-header-bar.ui
index ee76c1a..f730d75 100644
--- a/libide/workbench/ide-workbench-header-bar.ui
+++ b/libide/workbench/ide-workbench-header-bar.ui
@@ -15,18 +15,36 @@
       </packing>
     </child>
     <child type="title">
-      <object class="EggPriorityBox" id="center_box">
+      <object class="GtkBox" id="center_box">
         <property name="spacing">6</property>
         <property name="visible">true</property>
-        <!--
-          We might need separate children for center-right and center-left
-        -->
+        <child>
+          <object class="EggPriorityBox" id="center_left_box">
+            <property name="halign">end</property>
+            <property name="visible">true</property>
+          </object>
+          <packing>
+            <property name="pack-type">start</property>
+            <property name="fill">true</property>
+            <property name="expand">true</property>
+          </packing>
+        </child>
         <child type="center">
           <object class="IdeOmniBar" id="bar">
-            <property name="valign">center</property>
             <property name="visible">true</property>
           </object>
         </child>
+        <child>
+          <object class="EggPriorityBox" id="center_right_box">
+            <property name="halign">start</property>
+            <property name="visible">true</property>
+          </object>
+          <packing>
+            <property name="pack-type">end</property>
+            <property name="fill">true</property>
+            <property name="expand">true</property>
+          </packing>
+        </child>
       </object>
     </child>
     <child>
@@ -72,4 +90,12 @@
       </packing>
     </child>
   </template>
+  <object class="GtkSizeGroup">
+    <property name="mode">GTK_SIZE_GROUP_HORIZONTAL</property>
+    <widgets>
+      <!-- This is required due to bug https://bugzilla.gnome.org/show_bug.cgi?id=767932 -->
+      <widget name="center_right_box"/>
+      <widget name="center_left_box"/>
+    </widgets>
+  </object>
 </interface>