--- a/widget/src/qt/nsWindow.cpp
+++ b/widget/src/qt/nsWindow.cpp
@@ -138,16 +138,18 @@ nsWindow::GetThebesSurface()
         int width = mWidget->width(), height = mWidget->height();
 
         // Owen Taylor says this is the right thing to do!
         width = PR_MIN(32767, height);
         height = PR_MIN(32767, width);
 
         if (!gfxPlatform::UseGlitz()) {
             qDebug("QT_WIDGET NOT SURE: Func:%s::%d, [%ix%i]\n", __PRETTY_FUNCTION__, __LINE__, width, height);
+            // it works for example from http://www.figuiere.net/hub/blog/?2006/07/29/430-cairo-and-qt3
+            // but only with Qt3, with Qt4 we have same (nothing) result. :(
             mThebesSurface = new gfxXlibSurface
             (mWidget->x11Info().display(),
             (Drawable)mWidget->handle(),
              static_cast<Visual*>(mWidget->x11Info().visual()),
              gfxIntSize(width, height));
 
             // if the surface creation is reporting an error, then
             // we don't have a surface to give back