Resolves: tdf#138675 crash on checking if focus is in OFieldDescControl

use has_child_focus instead, which didn't exist at the time of...

commit 3fc63a7463149685b04c676968a82bc00a48a9af
Date:   Fri Aug 28 10:29:55 2020 +0100

    weld OTableBorderWindow

and so sidestep that m_pActFocusWindow has always fallen out of sync
when OFieldDescControl clears its contents

Change-Id: I274131c314a00bdfec2e877a2baa3758d45c325f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/109127
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
diff --git a/dbaccess/source/ui/control/FieldDescControl.cxx b/dbaccess/source/ui/control/FieldDescControl.cxx
index 2e0813d..bbd3951 100644
--- a/dbaccess/source/ui/control/FieldDescControl.cxx
+++ b/dbaccess/source/ui/control/FieldDescControl.cxx
@@ -1196,7 +1196,7 @@ bool OFieldDescControl::IsFocusInEditableWidget() const

bool OFieldDescControl::HasChildPathFocus() const
{
    return m_pActFocusWindow && m_pActFocusWindow->has_focus();
    return m_xContainer && m_xContainer->has_child_focus();
}

bool OFieldDescControl::isCopyAllowed()