Appears on non-primary screen

[probonopd]

The Dock can appear on another scren than the primary screen (the one that has the Menu).

https://github.com/cutefishos/dock/blob/main/src/mainwindow.cpp does quite some trickery with timers and whatnot to react to changes in screen geometry.

[probonopd]

However, this is not always the case.

This is working correctly:

(Note that DVI-D-1 is the screen that shows BIOS messages.)

[probonopd]

But with this, the Dock is not shown at all:

[probonopd]

And with this, the Dock is shown on the wrong screen (DVI-D-0) at the bottom of the screen, but not correctly centered for DVI-D-0 (looks like it is attempting it to center it to the width of DVI-I-1).

[probonopd]

So the whole thing is messed up. We need to backport the proper logic from https://github.com/cutefishos/dock.