I would like to use the “win-origin” config-variable to centre a game-window on the screen. However, under a dual-monitor setup its behaviour seems inconsistent: When the window is decorated, the variable works pretty much as one might expect. However, when the window is undecorated, it ends up centred within the full dual-monitor region, and thus split between the two monitors.
(I think that this was the reason that I chose the value of “-1” for the horizontal value of this config-variable in A Door to the Mists.)