Been a while since i installed GPS to GIMP.
1) Downloadf and extract the GPS Final.zip to your USERDIRECTORY/.gimp-2.8 folder.
2) Download and extract the extras zip file to your USERDIRECTORY/.gimp-2.8 folder also.
3) Download the sessionsrc file and open it in Notepad ++ or other text editor.
Select and copy all the contents of the file.
Make a backup copy of the current sessionsrc file in the .gimp-2.8 folder and put it somewhere safe like your desktop.
Inside Notepad ++ open the sessionsrc file that is currently inside the .gimp-2.8 folder. Now select all and paste the clipboard contents to the sessionsrc file and edit>save.
This will save the file as an RC file and NOT text.
IMPORTANT - The first two blocks have the monitor res set and you need to change them too your own.
For instance mine look like this
(session-info "toplevel"
(factory-entry "gimp-empty-image-window")
(position 0 0)
(size 1140 780))
(session-info "toplevel"
(factory-entry "gimp-single-image-window")
(position 0 0)
(size 1024 742)
(open-on-exit)
(aux-info
The new sessionsrc file looks like this
(session-info "toplevel"
(factory-entry "gimp-empty-image-window")
(position 0 0)
(size 1920 1025))
(session-info "toplevel"
(factory-entry "gimp-single-image-window")
(position 0 0)
(size 1920 1025)
(open-on-exit)
(aux-info
So i need to change those res numbers to my own.

So the new ones look like this.
(session-info "toplevel"
(factory-entry "gimp-empty-image-window")
(position 0 0)
(size 1140 780))
(session-info "toplevel"
(factory-entry "gimp-single-image-window")
(position 0 0)
(size 1024 742)
(open-on-exit)
(aux-info
(left-docks-width "65")
(right-docks-position "246"))
Now restart GIMP and it should look like this. Minus my theme of course.
SPLASHSCREEN!
INTERFACE
If you don't like the new layout just replace the current sessionsrc file with the backup on your desktop and your back to normal layout again.

Obviously it was intended for larger screen res so i will be changing mine back. Just wanted to show you how to get there.

Have fun!