Ok, I'm not even talking about the expansion map editor, I'm talking about any map editor, I got HOMM2 Gold Edition and finally got round to playing it but I have no map editor.
In my HOMM2 Gold files I have "EDITOR2" file which is 823KB, I open it, it requests permission to open, I give that and then it says that fullscreen mode is not supported (it is not set to open fullscreen). There is another file in this folder called "dosboxhomm2_editor.conf" (7.17KB) which when clicked on says "Windows wants to know what you want to open this program with it can either search online or you select from a list" but basically that won't open either.
Do I even have a map editor? Any clue at all? I'll put a bet on it being something really dumb and simple like last time.

You can open the dosboxhomm2_editor.conf with notepad, then you can look through it for fullscreen options. It would be easier to just run this from the start menu shortcut icon as it should already be configured to run properly.

It isn't configured properly... I tried opening the "dosboxhomm2_editor.conf" file in notepad, but none of it makes sense to me.

What happens when you use the start menu shortcut to the editor?

Copy and paste the contents on the forum and I'll have a look for you.

Ok will do.
# This is the configurationfile for DOSBox 0.72.
# Lines starting with a # are commentlines.
# They are used to (briefly) document the effect of each option.
[sdl]
# fullscreen -- Start dosbox directly in fullscreen.
# fulldouble -- Use double buffering in fullscreen.
# fullresolution -- What resolution to use for fullscreen: original or fixed size (e.g. 1024x768).
# windowresolution -- Scale the window to this size IF the output device supports hardware scaling.
# output -- What to use for output: surface,overlay,opengl,openglnb,ddraw.
# autolock -- Mouse will automatically lock, if you click on the screen.
# sensitiviy -- Mouse sensitivity.
# waitonerror -- Wait before closing the console if dosbox has an error.
# priority -- Priority levels for dosbox: lowest,lower,normal,higher,highest,pause (when not focussed).
# Second entry behind the comma is for when dosbox is not focused/minimized.
# mapperfile -- File used to load/save the key/event mappings from.
# usescancodes -- Avoid usage of symkeys, might not work on all operating systems.
fullscreen=true
fulldouble=false
fullresolution=original
windowresolution=original
output=overlay
autolock=true
sensitivity=100
waitonerror=true
priority=higher,normal
mapperfile=mapper.txt
usescancodes=true
[dosbox]
# language -- Select another language file.
# memsize -- Amount of memory DOSBox has in megabytes.
# machine -- The type of machine tries to emulate:hercules,cga,tandy,pcjr,vga.
# captures -- Directory where things like wave,midi,screenshot get captured.
language=
machine=svga_s3
captures=capture
memsize=16
[render]
# frameskip -- How many frames DOSBox skips before drawing one.
# aspect -- Do aspect correction, if your output method doesn't support scaling this can slow things down!.
# scaler -- Scaler used to enlarge/enhance low resolution modes.
# Supported are none,normal2x,normal3x,advmame2x,advmame3x,hq2x,hq3x,
# 2xsai,super2xsai,supereagle,advinterp2x,advinterp3x,
# tv2x,tv3x,rgb2x,rgb3x,scan2x,scan3x.
# If forced is appended (like scaler=hq2x forced), the scaler will be used
# even if the result might not be desired.
frameskip=0
aspect=false
scaler=normal2x
[cpu]
# core -- CPU Core used in emulation: normal,simple,dynamic,auto.
# auto switches from normal to dynamic if appropriate.
# cycles -- Amount of instructions DOSBox tries to emulate each millisecond.
# Setting this value too high results in sound dropouts and lags.
# You can also let DOSBox guess the correct value by setting it to max.
# The default setting (auto) switches to max if appropriate.
# cycleup -- Amount of cycles to increase/decrease with keycombo.
# cycledown Setting it lower than 100 will be a percentage.
core=auto
cycles=max
cycleup=500
cycledown=20
[mixer]
# nosound -- Enable silent mode, sound is still emulated though.
# rate -- Mixer sample rate, setting any devices higher than this will
# probably lower their sound quality.
# blocksize -- Mixer block size, larger blocks might help sound stuttering
# but sound will also be more lagged.
# prebuffer -- How many milliseconds of data to keep on top of the blocksize.
nosound=false
rate=22050
blocksize=2048
They're instructions I know but I'll be dammned if I know how to apply them.

Is that the whole file? Because that's only half of the config.
And mathboy's question is still valid: what happens when you use Start Menu shortcut?

If its having trouble opening the editor in fullscreen mode try just changing fullscreen=true to fullscreen=false and saving the file, will it open like that?

I can't even save it after I've edited it. :(
Sorry, I forgot to respond to mathboy's question.
Yes that is the whole file and I don't have an editor shortcut.

Seems to me installation is messed up. Have you tried reinstalling?
And this should be the first question, but what OS are we talking about here? ;)

Right click on the dosboxhomm2_editor.conf file and go to properties and then makes sure that the file isn't set to read only. Will be a checkbox at the bottom. Then if your running vista or win7 right click on the notepad and run as administrator. Make the fullscreen=false change and then save the file and it should save this time.
Edit: Just to clarify you need to find the notepad shortcut in your start menu under acessories and then right click that and run it as administrator. Then find and open the file.

I'm running it off a Toshiba Satellite L350D and Windows Vista Home Premium
I'm going to try uninstaling and reinstalling, I'll give you a shout if it works.

Just saying to be on the safe side - run the installer as admin, if you haven't done so first time.

Did all that but I've still got no map editor, it didn't put any shortcut other than the main game one on my desktop, the files are all the same.
:(