dnd: Don't allow drag-and-drop into or out of computer://.

The 'files' in this virtual location do not support it, so we
should never attempt it.

Clipboard operations do work, and are still supported.

Fixes linuxmint#3698

Author: mtwebster

eel/eel-vfs-extensions.c

@@ -76,6 +76,12 @@ eel_uri_is_network (const char *uri)
     return g_str_has_prefix (uri, "smb:") || g_str_has_prefix (uri, "network:");
 }
 
+gboolean
+eel_uri_is_computer (const char *uri)
+{
+    return g_str_has_prefix (uri, "computer:");
+}
+
 gboolean
 eel_vfs_supports_uri_scheme (const gchar *scheme)
 {

eel/eel-vfs-extensions.h

@@ -45,6 +45,7 @@ gboolean           eel_uri_is_search                     (const char           *
 gboolean           eel_uri_is_recent                     (const char           *uri);
 gboolean           eel_uri_is_favorite                   (const char           *uri);
 gboolean           eel_uri_is_network                    (const char           *uri);
+gboolean           eel_uri_is_computer                   (const char           *uri);
 gboolean           eel_vfs_supports_uri_scheme           (const gchar       *scheme);
 
 char *             eel_make_valid_utf8                   (const char           *name);

libnemo-private/nemo-dnd.c

@@ -492,6 +492,13 @@ nemo_drag_default_drop_action_for_icons (GdkDragContext *context,
         return;
     }
 
+    // compuuter:// uris do not support DND, don't allow it.
+    if (eel_uri_is_computer (target_uri_string) ||
+        eel_uri_is_computer (dropped_uri)) {
+        *action = 0;
+        return;
+    }
+
 	actions = gdk_drag_context_get_actions (context) & (GDK_ACTION_MOVE | GDK_ACTION_COPY);
 	if (actions == 0) {
 		 /* We can't use copy or move, just go with the suggested action. */