[geary] Replace some deprecated style calls in the composer with CSS rules.

[Michael Gratton <mjog src gnome org>]

commit 07b4a7842f4b5f019e1f3554f30db3ebe7147515
Author: Michael James Gratton <mike vee net>
Date:   Sun Apr 15 22:03:35 2018 +1000

    Replace some deprecated style calls in the composer with CSS rules.

 src/client/composer/composer-widget.vala |   26 +-------------------------
 ui/composer-widget.ui                    |    4 +++-
 ui/geary.css                             |   13 +++++++++++++
 3 files changed, 17 insertions(+), 26 deletions(-)
---
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index ec2d2c3..4ca7036 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -1846,34 +1846,10 @@ public class ComposerWidget : Gtk.EventBox {
         bool copy_link_enabled = hit_test.context_is_link();
         this.pointer_url = copy_link_enabled ? hit_test.get_link_uri() : null;
         this.message_overlay_label.label = this.pointer_url ?? "";
+        this.message_overlay_label.set_visible(copy_link_enabled);
         get_action(ACTION_COPY_LINK).set_enabled(copy_link_enabled);
     }
 
-    private void update_message_overlay_label_style() {
-        Gdk.RGBA window_background = container.top_window.get_style_context()
-            .get_background_color(Gtk.StateFlags.NORMAL);
-        Gdk.RGBA label_background = message_overlay_label.get_style_context()
-            .get_background_color(Gtk.StateFlags.NORMAL);
-        
-        if (label_background == window_background)
-            return;
-        
-        message_overlay_label.get_style_context().changed.disconnect(
-            on_message_overlay_label_style_changed);
-        message_overlay_label.override_background_color(Gtk.StateFlags.NORMAL, window_background);
-        message_overlay_label.get_style_context().changed.connect(
-            on_message_overlay_label_style_changed);
-    }
-
-    [GtkCallback]
-    private void on_message_overlay_label_realize() {
-        update_message_overlay_label_style();
-    }
-
-    private void on_message_overlay_label_style_changed() {
-        update_message_overlay_label_style();
-    }
-
     private bool on_context_menu(WebKit.WebView view,
                                  WebKit.ContextMenu context_menu,
                                  Gdk.Event event,
diff --git a/ui/composer-widget.ui b/ui/composer-widget.ui
index 7ecd48d..56d01d6 100644
--- a/ui/composer-widget.ui
+++ b/ui/composer-widget.ui
@@ -816,7 +816,9 @@
                         <property name="halign">start</property>
                         <property name="valign">end</property>
                         <property name="ellipsize">middle</property>
-                        <signal name="realize" handler="on_message_overlay_label_realize" swapped="no"/>
+                        <style>
+                          <class name="geary-overlay"/>
+                        </style>
                       </object>
                     </child>
                   </object>
diff --git a/ui/geary.css b/ui/geary.css
index 8508a7a..eec6250 100644
--- a/ui/geary.css
+++ b/ui/geary.css
@@ -32,6 +32,19 @@
   border-bottom-width: 0;
 }
 
+.geary-overlay {
+  background-color: @theme_base_color;
+  padding: 2px 6px;
+  border: 1px solid @borders;
+  border-bottom: 0;
+}
+.geary-overlay:dir(ltr) {
+  border-left: 0;
+}
+.geary-overlay:dir(rtl) {
+  border-right: 0;
+}
+
 .geary-titlebar-left:dir(ltr),
 .geary-titlebar-right:dir(rtl) {
   border-top-right-radius: 0px;