[evolution] Dropping text/* content to the editor is not handled by WebKit

[Tomas Popela <tpopela src gnome org>]

commit aba471941b94ff926930d7586f7567bdfae9fd6c
Author: Tomas Popela <tpopela redhat com>
Date:   Wed Apr 12 10:54:33 2017 +0200

    Dropping text/* content to the editor is not handled by WebKit
    
    The problem was that the WebKit failed to process the drag-drop signal as
    it internally failed to found its corresponding object to the
    GdkDragContext that was passed to it. The problem was that the
    corresponding object was removed when the drag-leave signal was
    processed by WebKit as it internally tries to postpone the drag-leave
    signal after the drag-drop is processed. As a solution we need to
    connect to the drag-leave signal, stop its emission and emit at after
    the drag-drop.
    
    In case where the drop is not handled by WebKit warn to the console (as
    this is not supposed to happen) and try to handle the drop ourselves.

 src/modules/webkit-editor/e-webkit-editor.c |   30 ++++++++++++++++++++++----
 1 files changed, 25 insertions(+), 5 deletions(-)
---
diff --git a/src/modules/webkit-editor/e-webkit-editor.c b/src/modules/webkit-editor/e-webkit-editor.c
index c907a8a..92f6751 100644
--- a/src/modules/webkit-editor/e-webkit-editor.c
+++ b/src/modules/webkit-editor/e-webkit-editor.c
@@ -5912,11 +5912,16 @@ webkit_editor_drag_data_received_cb (GtkWidget *widget,
            info == E_DND_TARGET_TYPE_UTF8_STRING || info == E_DND_TARGET_TYPE_STRING ||
            info == E_DND_TARGET_TYPE_TEXT_PLAIN || info == E_DND_TARGET_TYPE_TEXT_PLAIN_UTF8) {
                gdk_drag_status (context, gdk_drag_context_get_selected_action(context), time);
-               GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_drop (widget, context, x, y, time);
-               g_signal_stop_emission_by_name (widget, "drag-data-received");
-               if (!is_move)
-                       webkit_editor_call_simple_extension_function (wk_editor, 
"DOMLastDropOperationDidCopy");
-               e_content_editor_emit_drop_handled (E_CONTENT_EDITOR (widget));
+               if (!GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_drop (widget, context, x, y, 
time)) {
+                       g_warning ("Drop failed in WebKit");
+                       goto process_ourselves;
+               } else {
+                       GTK_WIDGET_CLASS (e_webkit_editor_parent_class)->drag_leave(widget, context, time);
+                       g_signal_stop_emission_by_name (widget, "drag-data-received");
+                       if (!is_move)
+                               webkit_editor_call_simple_extension_function (wk_editor, 
"DOMLastDropOperationDidCopy");
+                       e_content_editor_emit_drop_handled (E_CONTENT_EDITOR (widget));
+               }
                return;
        }
 
@@ -5926,6 +5931,7 @@ webkit_editor_drag_data_received_cb (GtkWidget *widget,
                gint list_len, len;
                gchar *text;
 
+ process_ourselves:
                data = gtk_selection_data_get_data (selection);
                length = gtk_selection_data_get_length (selection);
 
@@ -5954,6 +5960,16 @@ webkit_editor_drag_data_received_cb (GtkWidget *widget,
        }
 }
 
+static void
+webkit_editor_drag_leave_cb (EWebKitEditor *wk_editor,
+                             GdkDragContext *context,
+                             guint time)
+{
+       /* Don't pass drag-leave to WebKit otherwise the drop won't be handled by it.
+        * We will emit it later when WebKit is expecting it. */
+       g_signal_stop_emission_by_name (GTK_WIDGET (wk_editor), "drag-leave");
+}
+
 static gboolean
 webkit_editor_drag_drop_cb (EWebKitEditor *wk_editor,
                             GdkDragContext *context,
@@ -6283,6 +6299,10 @@ e_webkit_editor_init (EWebKitEditor *wk_editor)
                G_CALLBACK (webkit_editor_drag_end_cb), NULL);
 
        g_signal_connect (
+               wk_editor, "drag-leave",
+               G_CALLBACK (webkit_editor_drag_leave_cb), NULL);
+
+       g_signal_connect (
                wk_editor, "drag-drop",
                G_CALLBACK (webkit_editor_drag_drop_cb), NULL);