[evince] libview: Reset `pressed_button` when starting Drag and Drop

[Germán Poo-Caamaño <gpoo src gnome org>]

commit 92828bb797742e04aadbfdd62ba1da36837c37cf
Author: Jason Crain <jcrain src gnome org>
Date:   Sat Jul 14 20:50:54 2018 -0500

    libview: Reset `pressed_button` when starting Drag and Drop
    
    If view->pressed_button is left set, when the Drag and Drop operation
    completes, Evince will act as if it is still in a selection event.
    
    Fixes #754

 libview/ev-view.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/libview/ev-view.c b/libview/ev-view.c
index e6758944..bfe22ea3 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -5420,6 +5420,7 @@ ev_view_motion_notify_event (GtkWidget      *widget,
                                        1, (GdkEvent *)event);
 
                        view->selection_info.in_drag = FALSE;
+                       view->pressed_button = -1;
 
                        gtk_target_list_unref (target_list);
 
@@ -5440,6 +5441,7 @@ ev_view_motion_notify_event (GtkWidget      *widget,
                                        1, (GdkEvent *)event);
 
                        view->image_dnd_info.in_drag = FALSE;
+                       view->pressed_button = -1;
 
                        gtk_target_list_unref (target_list);