CanvasWindow: Use updateGL() when initializing the canvas after recre…

…ation

Calling updateGL() instead of update() works better on Windows; the
canvas switchover appears smoother and achieves similar behavior to
the Mac/X11 platform(s).

doomsday/engine/portable/src/canvaswindow.cpp

@@ -79,7 +79,7 @@ void CanvasWindow::initCanvasAfterRecreation(Canvas& canvas)
     self->d->canvas->makeCurrent();
     GL_Init2DState();
     self->d->canvas->doneCurrent();
-    self->d->canvas->update();
+    self->d->canvas->updateGL();
 
     // Reacquire the focus.
     self->d->canvas->setFocus();