"And you do introduce another iceberg: Tk and X-server."

I'm not sure what you mean. A daunting heap of problems in front of you; and an even greater mass, hidden from sight, waiting to sink your ship? :-)

I write a lot of Tk programs: many posted here; many more for personal use. I don't have any problems with the setup I described above.

I do have this file, in my home directory, which might help with some of your problems.

# .bash_vars

# To be sourced by .bash_profile.

# Use for potentially volatile environment variables.
# Saves having to make repeated edits to .bash_profile.
# Also, can be sourced independently.

set -a

# For X11
DISPLAY=:0
LIBGL_ALWAYS_INDIRECT=1

# ... irrelevant personal variables ...

# For Tk
XFT=1

# For Git
SSH_ASKPASS=

set +a
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