Ah - I forget to tell, which version I use. It is this one: 0.24 Beta for Linux from Debian

Package infos:
Package: wxhexeditor
Status: install ok installed
Priority: optional
Section: editors
Installed-Size: 1990
Maintainer: Andrej Shadura <andrewsh@debian.org>
Architecture: amd64
Source: wxhexeditor (0.24+repack-2)
Version: 0.24+repack-2+b2
Depends: libc6 (>= 2.34), libdisasm0 (>= 0.23), libgcc-s1 (>= 3.0), libgomp1 (>= 6), libmhash2 (>= 0.9.9.9), libstdc++6 (>= 5.2), libwxbase3.2-1 (>= 3.2.1+dfsg), libwxgtk3.2-1 (>= 3.2.1+dfsg-2)
Description: hexadecimal editor for massive files
 wxHexEditor is a hexadecimal file editor suitable
 for editing very big files. Supported file size
 is up to 2^64 bytes.
Homepage: https://github.com/EUA/wxHexEditor