(Solved) - Error starting gmoccapy

MX21, LCNC 2.9 RIP

Trying to start gmoccapy and I'm getting an error.  Only shows up in the terminal - no wrror windows.

Found file(REL): ./spindle_sim.hal
Found file(REL): ./simulated_home.hal
Traceback (most recent call last):
  File "/home/mill/linuxcnc-dev/bin/gmoccapy", line 43, in <module>
    import gladevcp.makepins   # needed for the dialog"s calculator widget
  File "/home/mill/linuxcnc-dev/lib/python/gladevcp/__init__.py", line 1, in <module>
    from .hal_pythonplugin import *
  File "/home/mill/linuxcnc-dev/lib/python/gladevcp/hal_pythonplugin.py", line 42, in <module>
    from .hal_sourceview import *
  File "/home/mill/linuxcnc-dev/lib/python/gladevcp/hal_sourceview.py", line 28, in <module>
    gi.require_version("GtkSource","3.0")
  File "/usr/lib/python3/dist-packages/gi/__init__.py", line 126, in require_version
    raise ValueError('Namespace %s not available' % namespace)
ValueError: Namespace GtkSource not available
Shutting down and cleaning up LinuxCNC...

axis, qtpyvcp screens, and qtvcp all start OK.

Some dependency thing?

EDIT - glade vcp demo also fails with the same error.

Appears to have GtkSource not installed, cause unknown. 

You might try to install the library, see

Installing the library did the trick, thanks a ton.