don't reopen current notebook on clicking its tree node

partial fix for #220 and #252
also catch null in mhas
indent
Revert "indent"

This reverts commit b3b51d1dde8b2c7c90cf2015a15a124c707c8f79.
Revert "also catch null in mhas"

This reverts commit 25036c7aa8619bbd4941e13175090282b18f4f2e.
indent and terminate line
fix null color domain bug
artifacts
fix function call and paren bugs

fixes #130