Turns out I was having two problems. First extending a selection by
holding real button 1 down doesn't work (you might mention this as an
additional side effect besides not being able to navigate a menu).
Second, gpm treats button 2 as the middle button when I was expecting
it to be the third (I don't normally use gpm). The upshot was that no
combination of the two buttons was letting me create a selection longer
than one character.
Yet another problem is that for some reason -M is not automatically
enabling -R for me, the repeater only works if I put -R after -M. (But
I'd figured that out earlier.)
I tried paddump and it shows me tapping every few seconds even when I
don't go near the pad. So until I figure out the virtual buttons I'll
stick to the real ones.
To get the real buttons to select anything, I add the flag -3 to gpm.
That way I can click on the left button, move to the othe end of the
selection (since dragging seems out), and click the right button. This
means I need Emulate3Buttons (click both) for pasting, but I can live
The upshot is that I can now use it! Thanks *very* much for doing this
neat hack, both Alan and Robin!