Resolves: tdf#151017 we now want the background to be the stock widget bg

Change-Id: I44a800748ffafe91f3b6169617be30ef87919267
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/140141
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/sfx2/source/dialog/backingwindow.cxx b/sfx2/source/dialog/backingwindow.cxx
index a50253b..a213009 100644
--- a/sfx2/source/dialog/backingwindow.cxx
+++ b/sfx2/source/dialog/backingwindow.cxx
@@ -172,9 +172,8 @@ BackingWindow::BackingWindow(vcl::Window* i_pParent)
    , mbLocalViewInitialized(false)
    , mbInitControls(false)
{
    // init background
    // init background, undo InterimItemWindow defaults for this widget
    SetPaintTransparent(false);
    SetBackground(svtools::ColorConfig().GetColorValue(::svtools::APPBACKGROUND).nColor);

    // square action button
    auto nHeight = mxFilter->get_preferred_size().getHeight();
@@ -362,6 +361,7 @@ void BackingWindow::ApplyStyleSettings()

    mxAllButtonsBox->set_background(aButtonsBackground);
    mxSmallButtonsBox->set_background(aButtonsBackground);
    SetBackground(aButtonsBackground);

    // compute the menubar height
    sal_Int32 nMenuHeight = 0;