Set_scale() on PGScrollFrame and PGButton

I created a PGScrollFrame with some PGButtons. I would like to create some kind of select buttons which are stacked onto each other.
When I scale the PGScrollFrame (and the Buttons) they seem to loose their bevel from time to time or the bevel is drawn in a different line width.
The first picture is created with a scale of 1 on the PGScrollFrame.Everything is ok here. Second and third picture is with a scale of 1.13 and 0.87. Here the missing or thicker lines are marked.

Thank you




This is the code used:

	// create PGScrollFrame
	PT(PGScrollFrame) pgsf = new PGScrollFrame("PGSFrame");
	NodePath pgsf_np = window->get_pixel_2d().attach_new_node(pgsf);
	pgsf_np.set_pos(300, 0, -500);
	pgsf_np.set_scale(1.0);	// this works fine

	for (int i = 1; i < 25; i++) {
		PT(PGButton) test_pgb = new PGButton("TestPGButton");
		test_pgb->setup(" ", 0.05f);		// no text just to make it easy to see

		//NodePath test_pgb_np = window->get_pixel_2d().attach_new_node(test_pgb);
		NodePath test_pgb_np = NodePath().attach_new_node(test_pgb);
		//NodePath test_pgb_np = pgsf_np.attach_new_node(test_pgb);
		test_pgb_np.set_pos(20, 0, -55.0f*i);

Does this only happen when the PGButtons are inside a PGScrollFrame?

Yes, only when the PGButtons are inside a PGScrollFrame.