diff --git a/src/client/accounts/account-dialog.vala b/src/client/accounts/account-dialog.vala
index a375cf60..ee95d134 100644
--- a/src/client/accounts/account-dialog.vala
+++ b/src/client/accounts/account-dialog.vala
@@ -24,8 +24,8 @@ public class AccountDialog : Gtk.Dialog {
         set_modal(true);
         set_titlebar (headerbar);
         get_content_area().margin_top = MARGIN;
-        get_content_area().margin_left = MARGIN;
-        get_content_area().margin_right = MARGIN;
+        get_content_area().margin_start = MARGIN;
+        get_content_area().margin_end = MARGIN;
         get_content_area().margin_bottom = MARGIN;
         
         // Add pages to stack.
diff --git a/src/client/composer/composer-headerbar.vala b/src/client/composer/composer-headerbar.vala
index 947597bb..3b378ed2 100644
--- a/src/client/composer/composer-headerbar.vala
+++ b/src/client/composer/composer-headerbar.vala
@@ -30,9 +30,9 @@ public class ComposerHeaderbar : PillHeaderbar {
         Gtk.Button detach_button = create_toolbar_button(null, ComposerWidget.ACTION_DETACH);
         detach_button.set_relief(Gtk.ReliefStyle.NONE);
         if (rtl)
-            detach_button.set_margin_left(6);
+            detach_button.set_margin_start(6);
         else
-            detach_button.set_margin_right(6);
+            detach_button.set_margin_end(6);
         detach_start.pack_start(detach_button);
         detach_start.pack_start(new Gtk.Separator(Gtk.Orientation.VERTICAL));
         
@@ -40,9 +40,9 @@ public class ComposerHeaderbar : PillHeaderbar {
         detach_button = create_toolbar_button(null, ComposerWidget.ACTION_DETACH);
         detach_button.set_relief(Gtk.ReliefStyle.NONE);
         if (rtl)
-            detach_button.set_margin_right(6);
+            detach_button.set_margin_end(6);
         else
-            detach_button.set_margin_left(6);
+            detach_button.set_margin_start(6);
         detach_end.pack_end(detach_button);
         detach_end.pack_end(new Gtk.Separator(Gtk.Orientation.VERTICAL));
         
diff --git a/src/client/dialogs/attachment-dialog.vala b/src/client/dialogs/attachment-dialog.vala
index 79884fa2..e391a351 100644
--- a/src/client/dialogs/attachment-dialog.vala
+++ b/src/client/dialogs/attachment-dialog.vala
@@ -94,8 +94,8 @@ public class AttachmentDialog : Gtk.FileChooserDialog {
         int larger_half = extra_space - smaller_half;
         
         // pad the image manually (avoids rounding errors)
-        preview_image.set_margin_left(PREVIEW_PADDING + smaller_half);
-        preview_image.set_margin_right(PREVIEW_PADDING + larger_half);
+        preview_image.set_margin_start(PREVIEW_PADDING + smaller_half);
+        preview_image.set_margin_end(PREVIEW_PADDING + larger_half);
         
         // show the preview
         preview_image.set_from_pixbuf(pixbuf);
diff --git a/ui/account_cannot_remove.glade b/ui/account_cannot_remove.glade
index 83a75614..ab8462de 100644
--- a/ui/account_cannot_remove.glade
+++ b/ui/account_cannot_remove.glade
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <!-- interface-requires gtk+ 3.0 -->
+  <!-- interface-requires gtk+ 3.14 -->
   <object class="GtkActionGroup" id="actions">
     <child>
       <object class="GtkAction" id="ok_action"/>
@@ -9,7 +9,7 @@
   <object class="GtkBox" id="container">
     <property name="visible">True</property>
     <property name="can_focus">False</property>
-    <property name="margin_left">1</property>
+    <property name="margin_start">1</property>
     <child>
       <object class="GtkImage" id="image1">
         <property name="visible">True</property>
diff --git a/ui/certificate_warning_dialog.glade b/ui/certificate_warning_dialog.glade
index e6ff2d33..cc89627f 100644
--- a/ui/certificate_warning_dialog.glade
+++ b/ui/certificate_warning_dialog.glade
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Generated with glade 3.16.1 -->
 <interface>
-  <requires lib="gtk+" version="3.10"/>
+  <requires lib="gtk+" version="3.14"/>
   <object class="GtkDialog" id="CertificateWarningDialog">
     <property name="can_focus">False</property>
     <property name="title" translatable="yes">Untrusted Connection</property>
@@ -12,8 +12,8 @@
     <child internal-child="vbox">
       <object class="GtkBox" id="dialog-vbox1">
         <property name="can_focus">False</property>
-        <property name="margin_left">12</property>
-        <property name="margin_right">12</property>
+        <property name="margin_start">12</property>
+        <property name="margin_end">12</property>
         <property name="margin_top">12</property>
         <property name="margin_bottom">12</property>
         <property name="orientation">vertical</property>
@@ -139,7 +139,7 @@
               <object class="GtkLabel" id="warnings_label">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
-                <property name="margin_left">16</property>
+                <property name="margin_start">16</property>
                 <property name="xalign">0</property>
                 <property name="label">(empty)</property>
                 <property name="wrap">True</property>
diff --git a/ui/composer.glade b/ui/composer.glade
index 84149959..a515db89 100644
--- a/ui/composer.glade
+++ b/ui/composer.glade
@@ -278,8 +278,8 @@
               <object class="GtkGrid" id="recipients">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
-                <property name="margin_left">6</property>
-                <property name="margin_right">6</property>
+                <property name="margin_start">6</property>
+                <property name="margin_end">6</property>
                 <property name="margin_top">6</property>
                 <property name="row_spacing">0</property>
                 <property name="column_spacing">6</property>
@@ -626,8 +626,8 @@
       <object class="GtkBox" id="attachments_box">
         <property name="visible">True</property>
         <property name="can_focus">False</property>
-        <property name="margin_left">6</property>
-        <property name="margin_right">6</property>
+        <property name="margin_start">6</property>
+        <property name="margin_end">6</property>
         <property name="margin_top">6</property>
         <property name="margin_bottom">6</property>
         <property name="orientation">vertical</property>
diff --git a/ui/find_bar.glade b/ui/find_bar.glade
index fee38d99..85ba52b0 100644
--- a/ui/find_bar.glade
+++ b/ui/find_bar.glade
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <!-- interface-requires gtk+ 3.0 -->
+  <!-- interface-requires gtk+ 3.14 -->
   <object class="GtkImage" id="image1">
     <property name="visible">True</property>
     <property name="can_focus">False</property>
@@ -46,7 +46,7 @@
             <property name="visible">True</property>
             <property name="can_focus">True</property>
             <property name="receives_default">True</property>
-            <property name="margin_right">6</property>
+            <property name="margin_end">6</property>
             <property name="image">image2</property>
             <property name="relief">none</property>
             <property name="always_show_image">True</property>
@@ -61,7 +61,7 @@
           <object class="GtkLabel" id="label: find">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
-            <property name="margin_right">2</property>
+            <property name="margin_end">2</property>
             <property name="yalign">0.4699999988079071</property>
             <property name="label" translatable="yes">Find:</property>
           </object>
@@ -90,7 +90,7 @@
             <property name="visible">True</property>
             <property name="can_focus">True</property>
             <property name="receives_default">True</property>
-            <property name="margin_left">2</property>
+            <property name="margin_start">2</property>
             <property name="image">image3</property>
             <property name="relief">none</property>
             <property name="use_underline">True</property>
@@ -126,8 +126,8 @@
             <property name="visible">True</property>
             <property name="can_focus">True</property>
             <property name="receives_default">False</property>
-            <property name="margin_left">8</property>
-            <property name="margin_right">8</property>
+            <property name="margin_start">8</property>
+            <property name="margin_end">8</property>
             <property name="relief">none</property>
             <property name="use_underline">True</property>
             <property name="xalign">0</property>
diff --git a/ui/login.glade b/ui/login.glade
index 0f768acc..a33bf862 100644
--- a/ui/login.glade
+++ b/ui/login.glade
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Generated with glade 3.16.1 -->
 <interface>
-  <requires lib="gtk+" version="3.10"/>
+  <requires lib="gtk+" version="3.14"/>
   <object class="GtkAdjustment" id="adjustment1">
     <property name="upper">100</property>
     <property name="step_increment">1</property>
@@ -883,7 +883,7 @@
             <property name="visible">True</property>
             <property name="can_focus">True</property>
             <property name="receives_default">False</property>
-            <property name="margin_left">12</property>
+            <property name="margin_start">12</property>
             <property name="use_underline">True</property>
             <property name="xalign">0</property>
             <property name="draw_indicator">True</property>
@@ -900,7 +900,7 @@
             <property name="visible">True</property>
             <property name="can_focus">True</property>
             <property name="receives_default">False</property>
-            <property name="margin_left">12</property>
+            <property name="margin_start">12</property>
             <property name="use_underline">True</property>
             <property name="xalign">0</property>
             <property name="draw_indicator">True</property>
@@ -916,7 +916,7 @@
             <property name="visible">True</property>
             <property name="sensitive">False</property>
             <property name="can_focus">False</property>
-            <property name="margin_left">12</property>
+            <property name="margin_start">12</property>
             <child>
               <placeholder/>
             </child>
diff --git a/ui/preferences.glade b/ui/preferences.glade
index 9b11e7d8..caf4e53a 100644
--- a/ui/preferences.glade
+++ b/ui/preferences.glade
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <requires lib="gtk+" version="3.10"/>
+  <requires lib="gtk+" version="3.14"/>
   <object class="GtkDialog" id="dialog">
     <property name="can_focus">False</property>
     <property name="border_width">12</property>
@@ -31,7 +31,7 @@
               <object class="GtkLabel" id="label1">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
-                <property name="margin_right">5</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="label" translatable="yes">Reading</property>
@@ -51,8 +51,8 @@
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
-                <property name="margin_left">12</property>
-                <property name="margin_right">5</property>
+                <property name="margin_start">12</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="use_underline">True</property>
@@ -70,8 +70,8 @@
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
-                <property name="margin_left">12</property>
-                <property name="margin_right">5</property>
+                <property name="margin_start">12</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="use_underline">True</property>
@@ -89,8 +89,8 @@
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
-                <property name="margin_left">12</property>
-                <property name="margin_right">5</property>
+                <property name="margin_start">12</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="use_underline">True</property>
@@ -106,7 +106,7 @@
               <object class="GtkLabel" id="label3">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
-                <property name="margin_right">5</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="label" translatable="yes">Composer</property>
@@ -126,8 +126,8 @@
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
-                <property name="margin_left">12</property>
-                <property name="margin_right">5</property>
+                <property name="margin_start">12</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="use_underline">True</property>
@@ -143,7 +143,7 @@
               <object class="GtkLabel" id="label4">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
-                <property name="margin_right">5</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="label" translatable="yes">Notifications</property>
@@ -163,8 +163,8 @@
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
-                <property name="margin_left">12</property>
-                <property name="margin_right">5</property>
+                <property name="margin_start">12</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="use_underline">True</property>
@@ -182,8 +182,8 @@
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
-                <property name="margin_left">12</property>
-                <property name="margin_right">5</property>
+                <property name="margin_start">12</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="use_underline">True</property>
@@ -202,8 +202,8 @@
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
                 <property name="tooltip_text" translatable="yes">Geary will run in the background and notify of new mail</property>
-                <property name="margin_left">12</property>
-                <property name="margin_right">5</property>
+                <property name="margin_start">12</property>
+                <property name="margin_end">5</property>
                 <property name="margin_top">5</property>
                 <property name="margin_bottom">5</property>
                 <property name="use_underline">True</property>
diff --git a/ui/remove_confirm.glade b/ui/remove_confirm.glade
index 5b1d3344..464fcb1c 100644
--- a/ui/remove_confirm.glade
+++ b/ui/remove_confirm.glade
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <!-- interface-requires gtk+ 3.0 -->
+  <!-- interface-requires gtk+ 3.14 -->
   <object class="GtkActionGroup" id="actions">
     <child>
       <object class="GtkAction" id="cancel_action"/>
@@ -12,7 +12,7 @@
   <object class="GtkBox" id="container">
     <property name="visible">True</property>
     <property name="can_focus">False</property>
-    <property name="margin_left">1</property>
+    <property name="margin_start">1</property>
     <child>
       <object class="GtkImage" id="image1">
         <property name="visible">True</property>
diff --git a/ui/upgrade_dialog.glade b/ui/upgrade_dialog.glade
index e2a138ed..792af946 100644
--- a/ui/upgrade_dialog.glade
+++ b/ui/upgrade_dialog.glade
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <!-- interface-requires gtk+ 3.6 -->
+  <!-- interface-requires gtk+ 3.14 -->
   <object class="GtkDialog" id="dialog">
     <property name="can_focus">False</property>
     <property name="border_width">5</property>
@@ -32,8 +32,8 @@
           <object class="GtkGrid" id="grid1">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
-            <property name="margin_left">8</property>
-            <property name="margin_right">8</property>
+            <property name="margin_start">8</property>
+            <property name="margin_end">8</property>
             <property name="margin_top">8</property>
             <property name="margin_bottom">8</property>
             <property name="row_spacing">8</property>