tdf#133690 Hide surrounding border frame at sidebar

Change-Id: I6daff0ae587232b4b31d02aeb2529eff3fba36a8
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/102967
Tested-by: Jenkins
Reviewed-by: Andreas Kainz <kainz.a@gmail.com>
diff --git a/vcl/source/window/splitwin.cxx b/vcl/source/window/splitwin.cxx
index 66d64e7..a099ed4 100644
--- a/vcl/source/window/splitwin.cxx
+++ b/vcl/source/window/splitwin.cxx
@@ -181,10 +181,6 @@ void SplitWindow::ImplDrawBorder(vcl::RenderContext& rRenderContext)
    switch (meAlign)
    {
    case WindowAlign::Bottom:
        rRenderContext.SetLineColor(rStyleSettings.GetShadowColor());
        rRenderContext.DrawLine(Point(0, 0), Point(nDX - 1, 0));
        rRenderContext.DrawLine(Point(0, nDY - 2), Point(nDX - 1, nDY - 2));

        rRenderContext.SetLineColor(rStyleSettings.GetLightColor());
        rRenderContext.DrawLine(Point(0, 1), Point(nDX - 1, 1));
        rRenderContext.DrawLine(Point(0, nDY - 1), Point(nDX - 1, nDY - 1));
@@ -211,14 +207,8 @@ void SplitWindow::ImplDrawBorder(vcl::RenderContext& rRenderContext)
        break;
    default:
        rRenderContext.SetLineColor(rStyleSettings.GetShadowColor());
        rRenderContext.DrawLine(Point(0, 0), Point( 0, nDY - 2));
        rRenderContext.DrawLine(Point(0, 0), Point( nDX - 1, 0));
        rRenderContext.DrawLine(Point(0, nDY - 2), Point(nDX - 1, nDY - 2));

        rRenderContext.SetLineColor( rStyleSettings.GetLightColor());
        rRenderContext.DrawLine(Point(1, 1), Point(1, nDY - 3));
        rRenderContext.DrawLine(Point(1, 1), Point(nDX - 1, 1));
        rRenderContext.DrawLine(Point(0, nDY - 1), Point(nDX - 1, nDY - 1));
        rRenderContext.DrawLine(Point(0, 0), Point( 0, nDY));
        rRenderContext.DrawLine(Point(0, nDY), Point(nDX, nDY));
    }
}

@@ -241,11 +231,6 @@ void SplitWindow::ImplDrawBorderLine(vcl::RenderContext& rRenderContext)
        rRenderContext.DrawLine( Point( nDX-SPLITWIN_SPLITSIZEEXLN, 1 ), Point( nDX-SPLITWIN_SPLITSIZEEXLN, nDY-3 ) );
        break;
    case WindowAlign::Right:
        rRenderContext.SetLineColor( rStyleSettings.GetShadowColor() );
        rRenderContext.DrawLine( Point( SPLITWIN_SPLITSIZEEXLN-1, 0 ), Point( SPLITWIN_SPLITSIZEEXLN-1, nDY-2 ) );

        rRenderContext.SetLineColor( rStyleSettings.GetLightColor() );
        rRenderContext.DrawLine( Point( SPLITWIN_SPLITSIZEEXLN, 1 ), Point( SPLITWIN_SPLITSIZEEXLN, nDY-3 ) );
        break;
    case WindowAlign::Top:
        rRenderContext.SetLineColor( rStyleSettings.GetShadowColor() );