On macOS 10.15, tk_getOpenFile shortly show all files or folders greyed.
It was not the case with 10.14 and it is not the case using the finder.
It seems very slow (proportional to the number of files).

Below a link to a video done with the basic script that is after.


menu .mbar
menu .mbar.open
.mbar.open add command -label "Open" -command { tk_getOpenFile }
.mbar add cascade -menu .mbar.open -label "Open"
. configure -menu .mbar