fix crash in CppunitTest_sw_uiwriter

Change-Id: I2411ce6d661f5bcbdc5e6d09f195ba6f15da24ba
diff --git a/vcl/source/window/toolbox.cxx b/vcl/source/window/toolbox.cxx
index d2e330b..f03a7ec 100644
--- a/vcl/source/window/toolbox.cxx
+++ b/vcl/source/window/toolbox.cxx
@@ -2664,7 +2664,7 @@ IMPL_LINK_NOARG(ToolBox, ImplDropdownLongClickHdl)
IMPL_LINK_NOARG(ToolBox, ImplUpdateHdl)
{

    if( mbFormat )
    if( mbFormat && mpData )
        ImplFormat();

    return 0;