Encourage disposed toolbox items to play nicely.

Change-Id: I4a28ba4740e9c84666cd85c046598862f20a7a96
diff --git a/vcl/source/window/toolbox2.cxx b/vcl/source/window/toolbox2.cxx
index 574705a..3b1ad8f 100644
--- a/vcl/source/window/toolbox2.cxx
+++ b/vcl/source/window/toolbox2.cxx
@@ -867,7 +867,7 @@ void ToolBox::SetPageScroll( bool b )

sal_uInt16 ToolBox::GetItemCount() const
{
    return (sal_uInt16)mpData->m_aItems.size();
    return mpData ? (sal_uInt16)mpData->m_aItems.size() : 0;
}

ToolBoxItemType ToolBox::GetItemType( sal_uInt16 nPos ) const
@@ -877,11 +877,13 @@ ToolBoxItemType ToolBox::GetItemType( sal_uInt16 nPos ) const

sal_uInt16 ToolBox::GetItemPos( sal_uInt16 nItemId ) const
{
    int nCount = mpData->m_aItems.size();
    for( int nPos = 0; nPos < nCount; nPos++ )
        if( mpData->m_aItems[nPos].mnId == nItemId )
            return (sal_uInt16)nPos;

    if (mpData)
    {
        int nCount = mpData->m_aItems.size();
        for( int nPos = 0; nPos < nCount; nPos++ )
            if( mpData->m_aItems[nPos].mnId == nItemId )
                return (sal_uInt16)nPos;
    }
    return TOOLBOX_ITEM_NOTFOUND;
}