I draw your attention
The widescreen patches (by JackFuste, 2012) has a bug that prevents Caesar3 + Zeus + Emperor (but not Pharaoh) from switching to Windowed mode.
(And it has nothing to do with Color Rendering not 16bit)
web.archive.org/web/20190910005136/www.wsgf.org/phpBB3/viewtopic.php?f=64&t=14149&start=160#p145033
@vempire_ghost, 23 Apr 2013
The problems runs on Zeus with Posseion on a 2.1 version.
Now after I apply the fix to my resolution (i have both pcs, one in 1980x1020 and another 1280x1024) I cannot put in window mode anymore, only if I set the 800x600 resolution, or revert back to the original .exe and use a 1024x728 standard resolution.
It depends on the value of only one byte.
When I noticed the difference in CRC32, XJDHDR explained the reason to me:
@XJDHDR
JackFuste found a problem where EXEs that he had patched were no longer able to be switched into Windowed mode (they were locked to Fullscreen). He then released a patching program that was attached to the forum post linked above which fixed this problem and made it possible to switch into Windowed mode again. I'm not sure why it works but the program replaces a "jump forward 0x6F bytes if EAX is less than ECX" into a "always jump forward 0x6F bytes" command. My widescreen pack, as you observed, come with this fix pre-applied whereas the other packs you found don't.
Outdated patches without patch "noWindowed" bug
www.moddb.com/mods/caesar-3-full-hd/downloads/caesar-iii-hd-support
XJDHDR Widescreen Pack 2018 with patched "noWindowed" bug
sourceforge.net/projects/xjdhdr-random-code/files/Game_related_files/City_Building_Strategy_Games_Series_files /
Now, if you're can't switch to Windowed Mode, then you know why.
Use a resizer from XJDHDR or apply a patch to the old ones.
After replacing .EXE with the patched one, you NEED to confirm in the Game that the new permission is applied and saved (in binary .INF)
We enter any mission, Menu =>Options =>Video =>"1024x768"
(it says "1024x768", but the real value will be what was replaced)