diff -up evolution-3.22.6/composer/e-msg-composer.c.composer-dnd evolution-3.22.6/composer/e-msg-composer.c

--- evolution-3.22.6/composer/e-msg-composer.c.composer-dnd	2017-04-13 14:06:08.863067766 +0200

+++ evolution-3.22.6/composer/e-msg-composer.c	2017-04-13 14:06:08.878067765 +0200

@@ -1867,6 +1867,16 @@ msg_composer_drag_drop_cb (GtkWidget *wi

 }

 static void

+msg_composer_drop_handled_cb (EContentEditor *cnt_editor,

+                              EMsgComposer *composer)

+{

+	if (composer->priv->drag_data_received_handler_id != 0) {

+		g_signal_handler_disconnect (cnt_editor, composer->priv->drag_data_received_handler_id);

+		composer->priv->drag_data_received_handler_id = 0;

+	}

+}

+

+static void

 msg_composer_drag_begin_cb (GtkWidget *widget,

                             GdkDragContext *context,

                             EMsgComposer *composer)

@@ -2272,6 +2282,10 @@ msg_composer_constructed (GObject *objec

 		G_CALLBACK (msg_composer_drag_begin_cb), composer);

 	g_signal_connect (

+		cnt_editor, "drop-handled",

+		G_CALLBACK (msg_composer_drop_handled_cb), composer);

+

+	g_signal_connect (

 		composer->priv->gallery_icon_view, "drag-data-get",

 		G_CALLBACK (msg_composer_gallery_drag_data_get), NULL);

diff -up evolution-3.22.6/e-util/e-content-editor.c.composer-dnd evolution-3.22.6/e-util/e-content-editor.c

--- evolution-3.22.6/e-util/e-content-editor.c.composer-dnd	2016-11-30 20:06:07.000000000 +0100

+++ evolution-3.22.6/e-util/e-content-editor.c	2017-04-13 14:06:08.878067765 +0200

@@ -36,6 +36,7 @@ enum {

 	CONTEXT_MENU_REQUESTED,

 	FIND_DONE,

 	REPLACE_ALL_DONE,

+	DROP_HANDLED,

 	LAST_SIGNAL

 };

@@ -509,6 +510,20 @@ e_content_editor_default_init (EContentE

 		NULL,

 		G_TYPE_NONE, 1,

 		G_TYPE_UINT);

+

+	/**

+	 * EContentEditor:drop-handled

+	 *

+	 * Emitted when the content editor successfully handled the drop operation.

+	 */

+	signals[DROP_HANDLED] = g_signal_new (

+		"drop-handled",

+		E_TYPE_CONTENT_EDITOR,

+		G_SIGNAL_RUN_LAST,

+		G_STRUCT_OFFSET (EContentEditorInterface, drop_handled),

+		NULL, NULL,

+		NULL,

+		G_TYPE_NONE, 0);

 }

 ESpellChecker *

@@ -3581,3 +3596,11 @@ e_content_editor_emit_replace_all_done (

 	g_signal_emit (editor, signals[REPLACE_ALL_DONE], 0, replaced_count);

 }

+

+void

+e_content_editor_emit_drop_handled (EContentEditor *editor)

+{

+	g_return_if_fail (E_IS_CONTENT_EDITOR (editor));

+

+	g_signal_emit (editor, signals[DROP_HANDLED], 0);

+}

diff -up evolution-3.22.6/e-util/e-content-editor.h.composer-dnd evolution-3.22.6/e-util/e-content-editor.h

--- evolution-3.22.6/e-util/e-content-editor.h.composer-dnd	2016-09-19 10:22:58.000000000 +0200

+++ evolution-3.22.6/e-util/e-content-editor.h	2017-04-13 14:06:08.878067765 +0200

@@ -437,6 +437,7 @@ struct _EContentEditorInterface {

 							 guint match_count);

 	void		(*replace_all_done)		(EContentEditor *editor,

 							 guint replaced_count);

+	void		(*drop_handled)			(EContentEditor *editor);

 };

 /* Properties */

@@ -1015,6 +1016,8 @@ void		e_content_editor_emit_find_done	(E

 void		e_content_editor_emit_replace_all_done

 						(EContentEditor *editor,

 						 guint replaced_count);

+void		e_content_editor_emit_drop_handled

+						(EContentEditor *editor);

 G_END_DECLS

diff -up evolution-3.22.6/modules/webkit-editor/e-webkit-editor.c.composer-dnd evolution-3.22.6/modules/webkit-editor/e-webkit-editor.c

--- evolution-3.22.6/modules/webkit-editor/e-webkit-editor.c.composer-dnd	2017-04-13 14:06:08.875067765 +0200

+++ evolution-3.22.6/modules/webkit-editor/e-webkit-editor.c	2017-04-13 14:06:28.256067497 +0200

@@ -5913,10 +5913,16 @@ webkit_editor_drag_data_received_cb (Gtk

 	    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");

+		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 +5932,7 @@ webkit_editor_drag_data_received_cb (Gtk

 		gint list_len, len;

 		gchar *text;

+ process_ourselves:

 		data = gtk_selection_data_get_data (selection);

 		length = gtk_selection_data_get_length (selection);

@@ -5949,10 +5956,21 @@ webkit_editor_drag_data_received_cb (Gtk

 		gtk_drag_finish (context, TRUE, is_move, time);

 		g_signal_stop_emission_by_name (widget, "drag-data-received");

+		e_content_editor_emit_drop_handled (E_CONTENT_EDITOR (widget));

 		return;

 	}

 }

+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,

@@ -6255,6 +6273,10 @@ e_webkit_editor_init (EWebKitEditor *wk_

 		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);