glxheads: exercise multiple GLX connections (any key = exit)
Usage:
  glxheads xdisplayname ...
Example:
  glxheads :0 mars:0 venus:1
Name: :0
  Display:     0x872910
  Window:      0x4800002
  Context:     0x89cfe0
  GL_VERSION:  3.3.0 NVIDIA 331.20
  GL_VENDOR:   NVIDIA Corporation
  GL_RENDERER: GeForce GT 325M/PCIe/SSE2