On my macOS 11.6.1 system, the test2 build with Tk 8.6.12 seems to work fine, generally. Wheew! *wipes brow* The list atom and individual element editing is great. I like the [file] implementation: light wrapper on the POSIX api.
# Help Browser
The right-most pane seems to have an update/refresh issue. It flashes to the background before redrawing and disappears if you navigate with the keys in one of the left-hand panes. I can look into this.
Also, I found that certain keybindings generate errors (not no TCL crashes), ex. undo.redo CMD+Z, etc.
# gatoms
Has the selection behavior changed? I see the gatom which receives the current focus now highlights but defocus seems to be inconsistent, at least to me. I would think that clicking into the atom, editing with the keyboard, then pressing enter or escape would defocus, but it doesn't. Is this new behavior? This also makes the behavior different form that of the IEM GUIs.
Also, it seems the focus highlight will stay if you double click to edit an atom which highlights the text, then click on another atom.
# Keybindings
I also agree that MOD+4 should remain as symbol atom and list atom can use MOD+6. I imagine the reasoning is that list atom can work with symbols so it's a decent replacement anyway, but I think this works against established muscle memory for some of us. OTOH I changed the HRadio keybinding from MOD+H to MOD+J so it could consistent on all platforms and we survived (CMD+H on macOS hides the window and is not overridable, oops!)...