[gtk] placesview: Set .error style if unsupported protocol

[Matthias Clasen <matthiasc src gnome org>]

commit 3bbfff9280106742df1c3c4582f07c6febffb392
Author: António Fernandes <antoniof gnome org>
Date:   Sat Nov 24 00:31:07 2018 +0000

    placesview: Set .error style if unsupported protocol
    
    When the user types an address with a schema that is not supported,
    the Connect button doesn't become sensitive, but there is no visible
    feedback at all.
    
    This feels unresponsive and leaves the user clueless.
    
    While it doesn't help explain why the address doesn't work, this will
    provide a hint that the input was acknowledged but doesn't work.
    
    https://gitlab.gnome.org/GNOME/gtk/issues/1476

 gtk/gtkplacesview.c | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/gtk/gtkplacesview.c b/gtk/gtkplacesview.c
index 693a28e3b3..be0a84ab15 100644
--- a/gtk/gtkplacesview.c
+++ b/gtk/gtkplacesview.c
@@ -1809,6 +1809,13 @@ on_address_entry_text_changed (GtkPlacesView *view)
 
 out:
   gtk_widget_set_sensitive (priv->connect_button, supported);
+  if (scheme && !supported)
+    gtk_style_context_add_class (gtk_widget_get_style_context (priv->address_entry),
+                                 GTK_STYLE_CLASS_ERROR);
+  else
+    gtk_style_context_remove_class (gtk_widget_get_style_context (priv->address_entry),
+                                    GTK_STYLE_CLASS_ERROR);
+
   g_free (address);
   g_free (scheme);
 }