Total Commander

It will be usefull to have a button (and a shortcut) to eject an external flash memory.

Why, there is already "Eject" in the context menu of a flash drive
and this can be reached in TC using severeal ways.

You mean something like

%SystemRoot%\System32\RUNDLL32.EXE shell32.dll,Control_RunDLL hotplug.dll


Also see e.g.
http://www.uwe-sieber.de/english.html
http://www.uwe-sieber.de/drivetools_e.html

for more specific tools.


Then just create an button with one of the commands.