tdf#153633 color description in chart colors options always black

even in dark mode. There are some other visual glitches here, just
erase the rendercontext before drawing to it.

Change-Id: I487375614c654124e116c3e9f28d78bf7f87da4e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/147087
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/svtools/source/control/valueset.cxx b/svtools/source/control/valueset.cxx
index 0693797..96f9405 100644
--- a/svtools/source/control/valueset.cxx
+++ b/svtools/source/control/valueset.cxx
@@ -255,16 +255,8 @@ IMPL_LINK(ValueSet, ImplScrollHdl, weld::ScrolledWindow&, rScrollWin, void)

void ValueSet::Paint(vcl::RenderContext& rRenderContext, const tools::Rectangle&)
{
    if (GetStyle() & WB_FLATVALUESET)
    {
        const StyleSettings& rStyleSettings = rRenderContext.GetSettings().GetStyleSettings();
        rRenderContext.SetLineColor();
        rRenderContext.SetFillColor(rStyleSettings.GetFaceColor());
        tools::Long nOffY = maVirDev->GetOutputSizePixel().Height();
        Size aWinSize(GetOutputSizePixel());
        rRenderContext.DrawRect(tools::Rectangle(Point(0, nOffY ), Point( aWinSize.Width(), aWinSize.Height())));
    }

    rRenderContext.SetBackground(Application::GetSettings().GetStyleSettings().GetFaceColor());
    rRenderContext.Erase();
    ImplDraw(rRenderContext);
}

@@ -1515,22 +1507,17 @@ void ValueSet::ImplDrawItemText(vcl::RenderContext& rRenderContext, const OUStri
    tools::Long nTxtWidth = rRenderContext.GetTextWidth(rText);
    tools::Long nTxtOffset = mnTextOffset;

    rRenderContext.Push(vcl::PushFlags::TEXTCOLOR);

    // delete rectangle and show text
    if (GetStyle() & WB_FLATVALUESET)
    {
        const StyleSettings& rStyleSettings = rRenderContext.GetSettings().GetStyleSettings();
        rRenderContext.SetLineColor();
        rRenderContext.SetFillColor(rStyleSettings.GetFaceColor());
        rRenderContext.DrawRect(tools::Rectangle(Point(0, nTxtOffset), Point(aWinSize.Width(), aWinSize.Height())));
        rRenderContext.SetTextColor(rStyleSettings.GetButtonTextColor());
    }
    else
    {
    const bool bFlat(GetStyle() & WB_FLATVALUESET);
    if (!bFlat)
        nTxtOffset += NAME_LINE_HEIGHT+NAME_LINE_OFF_Y;
        rRenderContext.SetBackground(Application::GetSettings().GetStyleSettings().GetFaceColor());
        rRenderContext.Erase(tools::Rectangle(Point(0, nTxtOffset), Point(aWinSize.Width(), aWinSize.Height())));
    }

    rRenderContext.SetTextColor(Application::GetSettings().GetStyleSettings().GetButtonTextColor());
    rRenderContext.DrawText(Point((aWinSize.Width() - nTxtWidth) / 2, nTxtOffset + (NAME_OFFSET / 2)), rText);

    rRenderContext.Pop();
}

void ValueSet::StyleUpdated()