Related: tdf#152637 Erase after changing background color

Change-Id: Ic63714304c32f066347a2654510e1fa1fbd16184
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/144721
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/cui/source/tabpages/numfmt.cxx b/cui/source/tabpages/numfmt.cxx
index f48a3b6..ea52910 100644
--- a/cui/source/tabpages/numfmt.cxx
+++ b/cui/source/tabpages/numfmt.cxx
@@ -135,6 +135,7 @@ void SvxNumberPreview::Paint(vcl::RenderContext& rRenderContext, const ::tools::
    svtools::ColorConfig aColorConfig;
    rRenderContext.SetTextColor(aColorConfig.GetColorValue(svtools::FONTCOLOR).nColor);
    rRenderContext.SetBackground(aColorConfig.GetColorValue(svtools::DOCCOLOR).nColor);
    rRenderContext.Erase();

    vcl::Font aDrawFont = rRenderContext.GetFont();
    Size aSzWnd(GetOutputSizePixel());