vcldemo: disable broken gradient stencil use.

Change-Id: Ifce85b1a7fa8e8b6fc57802a5fb559d2db50ba2a

vcl/opengl/gdiimpl.cxx

@@ -1373,6 +1373,8 @@ bool OpenGLSalGraphicsImpl::drawGradient(const tools::PolyPolygon& rPolyPoly,
 
     PreDraw();
 
+#define FIXME_BROKEN_STENCIL_FOR_GRADIENTS 0
+#if FIXME_BROKEN_STENCIL_FOR_GRADIENTS
     ImplSetClipBit( vcl::Region( rPolyPoly ), 0x02 );
     if( mbUseStencil )
     {
@@ -1384,6 +1386,7 @@ bool OpenGLSalGraphicsImpl::drawGradient(const tools::PolyPolygon& rPolyPoly,
         glEnable( GL_STENCIL_TEST );
         glStencilFunc( GL_EQUAL, 2, 0xFF );
     }
+#endif
 
     // if border >= 100%, draw solid rectangle with start color
     if( rGradient.GetBorder() >= 100.0 )
@@ -1408,8 +1411,10 @@ bool OpenGLSalGraphicsImpl::drawGradient(const tools::PolyPolygon& rPolyPoly,
         DrawRadialGradient( rGradient, aBoundRect );
     }
 
+#if FIXME_BROKEN_STENCIL_FOR_GRADIENTS
     if( !mbUseStencil )
         glDisable( GL_STENCIL_TEST );
+#endif
     PostDraw();
 
     CHECK_GL_ERROR();

vcl/workben/vcldemo.cxx

@@ -200,6 +200,7 @@ public:
 
     void drawBackground(OutputDevice &rDev, Rectangle r)
     {
+        rDev.Erase();
         Gradient aGradient;
         aGradient.SetStartColor(COL_BLUE);
         aGradient.SetEndColor(COL_GREEN);