vertex: I've just been able to make SWAT4 work like a charm on my multi-monitor high-res system. You'll need to modify the Swat4.ini in order to get SWAT4 into windowed mode, then use AutoHotkey to change position and size of that window.

1. open Swat4.ini that is located in your games installation folder at .\SWAT 4\Content\System\Swat4.ini

2. Search the line that reads
Suppress=WindowedMode
...and change it to...
;Suppress=WindowedMode

3. search the line that reads
StartupFullscreen=True
...and change it to...
StartupFullscreen=False

Now SWAT4 will launch in windowed mode. My first solution was to manually switch out of the window and launch the script after I launched SWAT4. But there's a more convenient way at the end. This is just to get the basic idea across:

4. create the AutoHotkey script:

WinMove, ahk_class Swat4UnrealWWindowsViewportWindow, , -3, -14, 2565, 1440
Exit

...and change the numbers to your needs. -3 is position from left, -14 is position from top, 2565 is window width and 1440 is height. This puts the window border on my 2560x1440 display juuust out of the screen area, so I can play almost "borderless full screen window" and the game scales nicely so far.

For the convenient way just create this AutoHotkey script:

Run, "E:\gog\Games\SWAT 4\Content\System\Swat4.exe" -nointro
WinWait, ahk_class Swat4UnrealWWindowsViewportWindow
WinActivate, ahk_class Swat4UnrealWWindowsViewportWindow
WinMove, ahk_class Swat4UnrealWWindowsViewportWindow, , -3, -14, 2565, 1440
Exit

...and use it to launch the game without intro, wait for the window to show and apply the move command. Just edit the path(!) and numbers to your liking as mentioned above.

UPDATE

You might need to change the ahk_class from

Swat4UnrealWWindowsViewportWindow
...to...
swat4UnrealWWindowsViewportWindow

(with a lower case s in the front). I'm not sure why, but this seems to vary. If it still doesn't budge, please use the AutoHotkey Window Spy to read the class of your window.

You could use the title - but if you're unlucky it'll move some browser window around if it carries the same title ;-)

vertex: Ah, thanks for the feedback. Glad to hear it still works :-)

TheAznGentleman: I'm not entirely sure how to create an AutoHotkey script?

vertex: Sorry for the late reply - it's been a while since I did this or played SWAT4. I'm not sure if this workaround will solve the flickering issue - but you can try running in windowed mode first - if that works, this fix is for you =)

In general:

1. install AutoHotkey which you can get here
https://www.autohotkey.com/

2. use the windows explorer to navigate to any location where you want to store your script

3. right click some empty space and chose "New » AutoHotkey Script" from the context menu

4. right click the new file and select "Edit Script" from the context menu

5. paste the script commands from the first post into it - then save and close

6. then launch the game, which will run in windowed mode

7. [Alt]+[Tab] out of the game and run the AutoHotkey script

If it doesn't work try changing the S to lower case in the script as described in the first post :)