Desperately seeking DragLock !!!

[Tom Horsley]

AAUGH! I can't live without drag lock for my trackball!

No doubt there is some totally new obscure undocumented
X input way to specify a mouse button to mean drag lock,
but the old way isn't recognized anymore (and the only place
in the xorg.conf man page that mentions an option with "drag"
in the name consists of the text "???" :-).

Before I go on the quest that may well lead to my death
buried in the darkest jungles of X11 source code, does anyone
happen to just know how I make a button do drag lock?

(For the folks who don't know what that is: I want to click
a button on my mouse and have that send button 1 press only
with no button release event till I click it again).