Make QGLWidgets have the same background colour as QWidgets

QWidgets are filled with Qt::transparent when WA_TranslucentBackground
is set, reguardless of what their background colour has been set to.
This patch makes QGLWidgets behave the same way.

Reviewed-By: Samuel Rødal

1 files changed, 8 insertions, 2 deletions

diff --git a/src/opengl/qpaintengine_opengl.cpp b/src/opengl/qpaintengine_opengl.cpp
index d5bf1dc..e3d8a1d 100644
--- a/src/opengl/qpaintengine_opengl.cpp
+++ b/src/opengl/qpaintengine_opengl.cpp
@@ -1330,9 +1330,15 @@ bool QOpenGLPaintEngine::begin(QPaintDevice *pdev)
 
     d->offscreen.begin();
 
-    const QColor &c = d->drawable.backgroundColor();
-    glClearColor(c.redF(), c.greenF(), c.blueF(), d->drawable.format().alpha() ? c.alphaF() : 1.0);
     if (d->drawable.context()->d_func()->clear_on_painter_begin && d->drawable.autoFillBackground()) {
+
+        if (d->drawable.hasTransparentBackground())
+            glClearColor(0.0, 0.0, 0.0, 0.0);
+        else {
+            const QColor &c = d->drawable.backgroundColor();
+            glClearColor(c.redF(), c.greenF(), c.blueF(), 1.0);
+        }
+
         GLbitfield clearBits = GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT;
 #ifndef QT_OPENGL_ES
         clearBits |= GL_ACCUM_BUFFER_BIT;