I'm using pygtkglext with vtk on both a mac and linux. I'm having a problem rendering multiple vtk actors on a mac. I only have the problem when using gtkglext to put vtk stuff in a gtk window -- I don't have the problem when I just use a regular vtk render window without gtk and gtkglext.
My python code renders an image volume using FixedPointVolumeRayCastMapper and another actor which is from the CubeSource, mapped with the PolyDataMapper. On the linux system I'm using (xorg version 7.1.0-16) this works fine. However, on a mac (xfree version 4.3), when the cube is added, the image volume disappears. When the cube is removed, the image comes back. When I run remotely on the linux system while displaying on a mac, I also have the disappearing image. When running remotely on the mac and displaying on linux, I don't have the disappearing image problem. This leads me to believe that there is some strange interaction between vtk and/or gtkglext and the X server on the mac.