[evolution] Make a magic-spacebar (partly) work again

[Milan Crha <mcrha src gnome org>]

commit 2d83196dbc1f0c3c6c4569f9a5c67ed079652ee4
Author: Milan Crha <mcrha redhat com>
Date:   Thu Aug 18 16:53:25 2016 +0200

    Make a magic-spacebar (partly) work again
    
    The missing part is scrolling of the web view, which doesn't work,
    because WebKit2 doesn't provide accurate numbers. More can be seen
    at https://bugs.webkit.org/show_bug.cgi?id=160958

 modules/mail/e-mail-shell-view-actions.c |   31 ++++++++++++++++++++++-------
 1 files changed, 23 insertions(+), 8 deletions(-)
---
diff --git a/modules/mail/e-mail-shell-view-actions.c b/modules/mail/e-mail-shell-view-actions.c
index d843671..e9aea63 100644
--- a/modules/mail/e-mail-shell-view-actions.c
+++ b/modules/mail/e-mail-shell-view-actions.c
@@ -1360,6 +1360,25 @@ action_mail_send_receive_send_all_cb (GtkAction *action,
        mail_send_immediately (session);
 }
 
+static GtkAdjustment *
+get_mail_display_scrolling_vadjustment (EMailDisplay *display)
+{
+       GtkWidget *window;
+
+       g_return_val_if_fail (E_IS_MAIL_DISPLAY (display), NULL);
+
+       if (GTK_IS_SCROLLABLE (display))
+               return gtk_scrollable_get_vadjustment (GTK_SCROLLABLE (display));
+
+       window = gtk_widget_get_parent (GTK_WIDGET (display));
+       if (GTK_IS_VIEWPORT (window))
+               window = gtk_widget_get_parent (window);
+       if (!GTK_IS_SCROLLED_WINDOW (window))
+               return NULL;
+
+       return gtk_scrolled_window_get_vadjustment (GTK_SCROLLED_WINDOW (window));
+}
+
 static void
 action_mail_smart_backward_cb (GtkAction *action,
                                EMailShellView *mail_shell_view)
@@ -1373,7 +1392,6 @@ action_mail_smart_backward_cb (GtkAction *action,
        EMailView *mail_view;
        GtkWidget *message_list;
        GtkToggleAction *toggle_action;
-       GtkWidget *window;
        GtkAdjustment *adj;
        EMailDisplay *display;
        GSettings *settings;
@@ -1403,11 +1421,10 @@ action_mail_smart_backward_cb (GtkAction *action,
        toggle_action = GTK_TOGGLE_ACTION (ACTION (MAIL_CARET_MODE));
        caret_mode = gtk_toggle_action_get_active (toggle_action);
 
-       window = gtk_widget_get_parent (GTK_WIDGET (display));
-       if (!GTK_IS_SCROLLED_WINDOW (window))
+       adj = get_mail_display_scrolling_vadjustment (display);
+       if (!adj)
                return;
 
-       adj = gtk_scrolled_window_get_vadjustment (GTK_SCROLLED_WINDOW (window));
        value = gtk_adjustment_get_value (adj);
        if (value == 0) {
 
@@ -1457,7 +1474,6 @@ action_mail_smart_forward_cb (GtkAction *action,
        EMailReader *reader;
        EMailView *mail_view;
        GtkWidget *message_list;
-       GtkWidget *window;
        GtkAdjustment *adj;
        GtkToggleAction *toggle_action;
        EMailDisplay *display;
@@ -1489,11 +1505,10 @@ action_mail_smart_forward_cb (GtkAction *action,
        toggle_action = GTK_TOGGLE_ACTION (ACTION (MAIL_CARET_MODE));
        caret_mode = gtk_toggle_action_get_active (toggle_action);
 
-       window = gtk_widget_get_parent (GTK_WIDGET (display));
-       if (!GTK_IS_SCROLLED_WINDOW (window))
+       adj = get_mail_display_scrolling_vadjustment (display);
+       if (!adj)
                return;
 
-       adj = gtk_scrolled_window_get_vadjustment (GTK_SCROLLED_WINDOW (window));
        value = gtk_adjustment_get_value (adj);
        upper = gtk_adjustment_get_upper (adj);
        if (value + gtk_adjustment_get_page_size (adj) >= upper) {