Miranda 0.10.21 snap-to-monitor-border-feature does not reduce the desktops size

A follow-up-issue of CORE-14439 (of minor importance just)

Reproduction steps

• install Miranda 0.10.21 from rapps and start its main app
• Create a new profile and drag the contact list to the right side of the screen
• It will snap to the border, good, but

Observed result
The desktop does not reduce in horizontal size then, e.g. when starting an explorer fiolebrowser afterwards and maximizing it, it will erroneously cover the full screen
We log

fixme:(dll/win32/shell32/wine/appbar.c:102) unknown msg: 1

fixme:(dll/win32/shell32/wine/appbar.c:102) unknown msg: 9

which does seem heavily related.
0.4.13-RC-53-g4f628f6_affected.webm
0.4.13-RC-53-g4f628f6_affected.log

Expected result
on 2k3sp2 the desktops size will shrink horizontally, effectively always keeping Mirandas contact list visible, even when maximizing an explorer window
2k3sp2_ok.webm

I have not tested yet, but I am 99.999999% sure, that master 0.4.14-dev-1222-g94f6db2 would behave the same, as it uses the same state of the appbar implementation, that I just ported back into 0.4.13RC.