This fixes T51143. gl_ClipDistance is part of GLSL version 1.3 but Mac is stuck on 1.2 for now. This workaround uses GPU_SHADER_3D_UNIFORM_COLOR for the entire rotation widget, ignoring any clipping plane. The CLIPPING shader only works on GLSL 1.3+ so I removed its 1.2 cruft. A legacy implementation using gl_ClipVertex might be possible, but is not worth the effort. This problem (and workaround) goes away when all platforms move to 3.3 core profile.