[kai] Conclusion
A) APL characters should to be entered (and tested!) in an APL session. Full
stop.
B) In APL there are two keyboard modes: "Standard" and "APL"


Kai,

As someone who has been tinkering with keyboards for many years, I feel your
pain. But don’t we already have 98% of what you are asking for? Except for
a "slight change of background color" that accompanies a change in keyboard
mode, everything that you discuss is achievable now.

The interesting thing is that with the advent of Version 12 and Dyalog's Unicode
interpreter control of the keyboard is now in the domain of the operating system
and not the APL vendor. By going to the "Text Services and Input Languages"
dialog through the Control Panel it's easy to set-up a "Standard" and "APL"
keyboard mode. And it allows you to declare Hotkeys for the purpose of toggling
back & forth. Since keyboard mode is now a function of the Windows Operating
System, these separate modes are available not just within APL but within other
apps like FireFox and Notepad. In Firefox, should Ctrl-T open a new window or
print a "tilde"? Now it's a function of your operating system-defined keyboard
mode. Each user gets to choose for himself, I think that's progress.

It's true that the choice of keyboards that Dyalog provides in Version 12 so far
are limited. But you are not compelled to use the their Unified definition.
Using the "Microsoft Keyboard Layout Creator" you can tweak their definition or
create a classical APL keyboard, if that's your preference.

-Jim Goff

P.S. All of this works without an IME *

* An IME (Input Method Editor) is a separate program that must run alongside the
main application. It actively manages the mapping of non-simple keyboard input
which is necessary when number of possible characters exceeds the number of keys
on the keyboard.