GNOME Bugzilla – Bug 642514
GtkViewPort draws a frame even with shadow_type = GTK_SHADOW_NONE
Last modified: 2014-12-06 05:01:23 UTC
Now, GtkViewPort, always draw a shadow around the widget even if the property is set to GTK_SHADOW_NONE. It happens using the recent release GTK 3.0.0. It was working not a long time ago but I don't remember exactly which version I was using previously. I suspect it comes from the commit 6f3706ac28abb6e45f4aef9534daa3a6b435c2d0. I don't know exactly how it's working but gtk_scrolled_window_draw is calling gtk_render_frame only if shadow_type is not equal to GTK_SHADOW_NONE.
this is no longer the case