Let's fill the unstyled EffectFrame texture with black instead of white. So the texture modulate still produces the correct color and the shader has the correct color.

Correctly inverted colors in PresentWindows with invert effect.

svn path=/trunk/KDE/kdebase/workspace/; revision=962235

lib/kwineffects.cpp

@@ -1816,7 +1816,7 @@ void EffectFrame::updateUnstyledTexture()
     QPainter p( &tmp );
     p.setRenderHint( QPainter::Antialiasing );
     p.setPen( Qt::NoPen );
-    p.setBrush( Qt::white );
+    p.setBrush( Qt::black );
     p.drawEllipse( tmp.rect() );
     p.end();
 #undef CS