restore focus to the GtkEntry of GtkComboBoxText on menu popdown

the font size/name dropdowns in the document toolbar should continue
to restore focus to the document directly while typical ones should
vcl-alike select the GtkEntry contents

Change-Id: Ic6c6cd48362dac6e4476c42a4070a83cd50faa2b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/115104
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/vcl/unx/gtk3/gtk3gtkinst.cxx b/vcl/unx/gtk3/gtk3gtkinst.cxx
index 65a530f..afb3aeb 100644
--- a/vcl/unx/gtk3/gtk3gtkinst.cxx
+++ b/vcl/unx/gtk3/gtk3gtkinst.cxx
@@ -14684,11 +14684,13 @@ private:
        {
            m_bPopupActive = bIsShown;
            ComboBox::signal_popup_toggled();
            if (!m_bPopupActive)
            if (!m_bPopupActive && m_pEntry)
            {
                //restore focus to the entry view when the popup is gone, which
                disable_notify_events();
                //restore focus to the GtkEntry when the popup is gone, which
                //is what the vcl case does, to ease the transition a little
                grab_focus();
                gtk_widget_grab_focus(m_pEntry);
                enable_notify_events();
            }
        }
    }