"Steven T. Hatton"
It would be nice to have a speciall key sequence to switch quickly between key mappings (I believe the KDE actually does support this.),
Yes.
But I don't think that switching keyboard layouts all the time is a
sensible solution if you need to input many different characters. You
will never be able to type fast, because you can't get use to all
keyboard layouts at the same time.
I believe it is better for typing speed to learn touch typing for
*one* keyboard layout and enter the other characters with some input
method.
For example, I always use the US keyboard layout and usually type
German in XEmacs in iso-accents-mode, i.e. I type "o and XEmacs
converts that to ö. Similar to dead keys. You can also use compose
for that. For example, if the
/usr/X11R6/lib/X11/locale/en_US.UTF-8/Compose contains