client: Use natural width intead of CSS min-width

#1516

src/client/conversation-list/conversation-list-view.vala

@@ -105,6 +105,11 @@ public class ConversationList.View : Gtk.ScrolledWindow, Geary.BaseInterface {
         }
     }
 
+    public override void get_preferred_width(out int minimum_size, out int natural_size) {
+        minimum_size = 300;
+        natural_size = 500;
+    }
+
     /**
      * Updates the display of the received time on each list row.
      *

src/client/conversation-viewer/conversation-viewer.vala

@@ -151,6 +151,11 @@ public class ConversationViewer : Gtk.Stack, Geary.BaseInterface {
         base_unref();
     }
 
+    public override void get_preferred_width(out int minimum_size, out int natural_size) {
+        minimum_size = 300;
+        natural_size = 700;
+    }
+
     /**
      * Puts the view into composer mode, showing a full-height composer.
      */

src/client/folder-list/folder-list-tree.vala

@@ -48,6 +48,11 @@ public class FolderList.Tree : Sidebar.Tree, Geary.BaseInterface {
         base_unref();
     }
 
+    public override void get_preferred_width(out int minimum_size, out int natural_size) {
+        minimum_size = 300;
+        natural_size = 500;
+    }
+
     public void set_has_new(Geary.Folder folder, bool has_new) {
         FolderEntry? entry = get_folder_entry(folder);
         if (entry != null) {

ui/conversation-list-view.ui

@@ -3,7 +3,6 @@
 <interface>
   <requires lib="gtk+" version="3.24"/>
   <template class="ConversationListView" parent="GtkScrolledWindow">
-    <property name="width-request">250</property>
     <property name="visible">True</property>
     <property name="can-focus">False</property>
     <child>

ui/geary.css

@@ -8,22 +8,10 @@
 
 /* MainWindow */
 
-.geary-folder {
-  min-width: 300px;
-}
-
 geary-conversation-list revealer {
   margin: 6px;
 }
 
-geary-conversation-list {
-  min-width: 360px;
-}
-
-geary-conversation-viewer {
-  min-width: 360px;
-}
-
 .geary-overlay {
   background-color: @theme_base_color;
   padding: 2px 6px;