Index: gtk2_ardour/missing_plugin_dialog.cc
===================================================================
--- gtk2_ardour/missing_plugin_dialog.cc	(revision 10493)
+++ gtk2_ardour/missing_plugin_dialog.cc	(working copy)
@@ -32,6 +32,7 @@
         set_session (s);
 
         add_button (_("OK"), RESPONSE_OK);
+        set_default_response (RESPONSE_OK);
 
 	Label* m = manage (new Label);
 
Index: gtk2_ardour/new_plugin_preset_dialog.cc
===================================================================
--- gtk2_ardour/new_plugin_preset_dialog.cc	(revision 10499)
+++ gtk2_ardour/new_plugin_preset_dialog.cc	(working copy)
@@ -41,6 +41,8 @@
 
 	add_button (Stock::CANCEL, RESPONSE_CANCEL);
 	_add = add_button (Stock::ADD, RESPONSE_ACCEPT);
+	set_default_response (RESPONSE_ACCEPT);
+	_name.set_activates_default(true);
 
 	show_all ();
 
Index: gtk2_ardour/missing_file_dialog.cc
===================================================================
--- gtk2_ardour/missing_file_dialog.cc	(revision 10493)
+++ gtk2_ardour/missing_file_dialog.cc	(working copy)
@@ -43,6 +43,7 @@
         set_session (s);
 
         add_button (_("Done"), RESPONSE_OK);
+        set_default_response (RESPONSE_OK);
 
         string typestr;