fix #547

resources/history_dialog.ui

 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.20.0 -->
+<!-- Generated with glade 3.22.1 -->
 <interface>
   <requires lib="gtk+" version="3.20"/>
   <template class="PamacHistoryDialog" parent="GtkDialog">
@@ -11,6 +11,9 @@
     <property name="default_height">500</property>
     <property name="icon_name">system-software-install</property>
     <property name="type_hint">dialog</property>
+    <child>
+      <placeholder/>
+    </child>
     <child internal-child="vbox">
       <object class="GtkBox" id="dialog-vbox1">
         <property name="can_focus">False</property>
@@ -24,7 +27,7 @@
                 <property name="label" translatable="yes">_Close</property>
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
-                <property name="receives_default">False</property>
+                <property name="receives_default">True</property>
                 <property name="use_underline">True</property>
               </object>
               <packing>
@@ -70,8 +73,5 @@
     <action-widgets>
       <action-widget response="-7">close_button</action-widget>
     </action-widgets>
-    <child>
-      <placeholder/>
-    </child>
   </template>
 </interface>

resources/progress_dialog.ui

 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.20.0 -->
+<!-- Generated with glade 3.22.1 -->
 <interface>
   <requires lib="gtk+" version="3.20"/>
   <template class="PamacProgressDialog" parent="GtkApplicationWindow">
@@ -10,6 +10,9 @@
     <property name="default_width">600</property>
     <property name="icon_name">system-software-install</property>
     <property name="deletable">False</property>
+    <child>
+      <placeholder/>
+    </child>
     <child>
       <object class="GtkBox" id="box">
         <property name="visible">True</property>
@@ -51,7 +54,7 @@
                 <property name="label" translatable="yes">_Close</property>
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
-                <property name="receives_default">False</property>
+                <property name="receives_default">True</property>
                 <property name="use_underline">True</property>
               </object>
               <packing>

resources/transaction_sum_dialog.ui

@@ -45,7 +45,7 @@
                 <property name="label" translatable="yes">Commit</property>
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
-                <property name="receives_default">False</property>
+                <property name="receives_default">True</property>
               </object>
               <packing>
                 <property name="expand">False</property>
@@ -58,7 +58,7 @@
                 <property name="label" translatable="yes">Edit build files</property>
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
-                <property name="receives_default">False</property>
+                <property name="receives_default">True</property>
               </object>
               <packing>
                 <property name="expand">False</property>

src/transaction-gtk.vala

@@ -248,8 +248,9 @@ namespace Pamac {
 			dialog.border_width = 6;
 			dialog.icon_name = "system-software-install";
 			dialog.deletable = false;
-			dialog.add_button (dgettext (null, "Trust and Import"), Gtk.ResponseType.OK);
-			unowned Gtk.Widget widget = dialog.add_button (dgettext (null, "_Cancel"), Gtk.ResponseType.CANCEL);
+			unowned Gtk.Widget widget = dialog.add_button (dgettext (null, "Trust and Import"), Gtk.ResponseType.OK);
+			widget.receives_default = true;
+			widget = dialog.add_button (dgettext (null, "_Cancel"), Gtk.ResponseType.CANCEL);
 			widget.can_focus = true;
 			widget.has_focus = true;
 			widget.can_default = true;
@@ -488,8 +489,9 @@ namespace Pamac {
 														application_window,
 														flags);
 				dialog.icon_name = "system-software-install";
-				dialog.add_button (dgettext (null, "Save"), Gtk.ResponseType.CLOSE);
-				unowned Gtk.Widget widget = dialog.add_button (dgettext (null, "_Cancel"), Gtk.ResponseType.CANCEL);
+				unowned Gtk.Widget widget = dialog.add_button (dgettext (null, "Save"), Gtk.ResponseType.CLOSE);
+				widget.receives_default = true;
+				widget = dialog.add_button (dgettext (null, "_Cancel"), Gtk.ResponseType.CANCEL);
 				widget.can_focus = true;
 				widget.has_focus = true;
 				widget.can_default = true;