Eddie’s Office 2013 Theme Mod



Ok guys, I’ve been having my eyeballs burned long enough, and so a couple of days ago I figured I’d give it a go, trying to find a way so sort this out. Shortly after starting out, I found this site which provided some good ideas. I was just about to give up, when I did a final attempt, and it seems to have paid off.

It’s early times, but I’ve managed to replace some colours. I’d figured I’d share what I’ve found so that others can help figure out the rest.

Here is a screenshot of what I’ve managed to achieve: https://dl.dropboxusercontent.com/u/8452679/images/OutlookModifiedColours.png

Step-by-step how I got there:
1. First I switched between different themes to find out which colours changed and then I picked one that stood out. The one I chose was the bottom status bar which is grey in the “Dark Grey” theme, but is light-blue in the “Light Grey” theme. I grabbed a screenshot of the light-blue colour, and grabbed the hex colour code in Photoshop (0067b0)

2. I searched for all the .dll file in the below locations (incl. subdirs) and copied them to a couple of temp folders (Test & Test2).
C:\Program Files\Microsoft Office\Office15
C:\Program Files\Common Files\Microsoft Shared\OFFICE15

3. I opened up a .dll file in HxD (mh-nexus.de/hxd/) and replaced three bytes of HEX with ones from the light-blue colour (replaced “00 00 00″ with “00 67 b0″). This gave me the light-blue equivalent string “.g°”

I used grep to search all the .dll files for this string using the below commands which gave me a list of .dll files.
grep .g° “C:\Test\*.dll”
grep .g° “C:\Test2\*.dll”

4. I opened the files one by one using HxD and then searching for the string. Most of the files didn’t seem to contain colour codes (the strings found were in random places), but in the file MSO.DLL the strings were all lined up with what seemed to be other color code strings.

5. I replaced all the HEX bytes (00 67 B0) found with a pink color (FF 00 FF) and then saved as a new file (MSO.DLL.modified).

6. When I tried to rename the original MSO.DLL file (to MSO.DLL.original), it complained about being in use, so restarted and then it worked. I renamed my modified file to MSO.DLL and then copied this to the original file’s location (C:\Program Files\Common Files\Microsoft Shared\OFFICE15)

7. After starting Outlook, I switched theme from Dark Grey to Light Gray and voila, some colours had changed! Note that the colour of the status bar that I tried chaning didn’t change, so this is most likely defined in another .dll file.

Using the above method, one should be able to change one colour after another to figure out which colours do what and then create a map of all colours that can be changed.



Great job Eddie. I followed your lead with a few teaks and was able to customize the color for the “unread emails” to FF 00 FF. Note to others I did have to force several processes to close that were using the MSO.dll file before I was able to copy my edited version back into the original location.
See Here: https://www.dropbox.com/s/6v3sd0wq0liuk5j/Screen%20Shot%20Custom.jpg?dl=0

– ushadow91

Cheers guys,

Just to let you understand why it’s taking so long. For the dark theme only, there are 2568 colours you can change and a total of 900 unique colours. Not sure what the guys were thinking when designing the themes.

Anyways, I’m mapping whatever I can find visually after changing to random colours. I’m almost done with Outlook, and I’ve mapped about 60 items (backgrounds, text, borders etc.) so far.

Once done I will create a dark theme with maybe 20 colours in total which should help in designing themes going forward. It’s a big job and sometimes I feel like giving up, but it only needs to done once properly for everyone to benefit.

– Eddie

“… I still would like to change the colors to something other than the dark one. Maybe you can give us another update on the location of all the files/reg that need to be mapped. I can maybe help out! I really want this too!


– Jason


Hi Jason,
Sorry I haven’t had a chance to get back into this due to being busy with life 🙂
However I’m still dedicated to finish this off. I do appreciate the offer to help. Let me explain where I’m at and you can decide if you would like to help.
I’ve created two new versions of MSO.dll where I’ve replaced all colours (well half in the first and half in the second – I had to split it up into two as I didn’t have enough random replacement colours at hand). What I need help with is to finish mapping out what colours have changed (after you replace the MSO.dll file).

You do this by…

A. Visually taking note of colours that have changed.

B. Taking a screenshot, then checking which colour it is (in HEX – I use Photoshop).

C. Add the hex into a spreadsheet which automatically matches the hex to the random colour. The offset is also automatically calculated which will be used to change the colours in the final script.

D. Note down the section, type and item description so that we know what the colour/entry relates to.

Note that finishing off mapping out all the colours (well the main ones at least) will take many hours/days to complete.

If you’re still interested let me know and I’ll send you files/instructions per email (or other preferred method of communication).

Help with this would allow me to focus on finishing of the script/theme-files part of the work.


– Eddie


Ok, I’ve now got a working script that will replace colours at specific offsets (from start of dark theme section). All I need now is a theme in the form of a .csv file with offsets and replacement colours. As I have most of the Outlook parts mapped out already, I will start creating a dark theme based on this info. Once I’m happy with this I will release a beta version of the script and theme for people to try out. Won’t give an ETA for this but this is one of the last pieces of the puzzle. Once I’ve got a theme sorted, I’ll look into mapping out the remaining colours for Word, Excel etc. and create instructions for ppl to create their own themes.

– Eddie


99 thoughts on “Eddie’s Office 2013 Theme Mod

  1. Hi guys,

    do we have the dll file available somwhere already please? It would help a lot to get it about now. 🙂


  2. Interesting. You’ve managed to sort things out with effort and dedication. I understand there’s no one click installer for this, but I think you really should share at least a DLL file (the one you talked about: MSO.DLL) with at least a grey background color for the preview pane. I think this is the minimun color people are lloking forward to change. The dedication for a theme, a scrip’t and a way to let people change the look of Outlook made easy is awesome and great, but please consider a mini how to like: “1) Download this file; 2) To to path X and replace it; 3) You have a grey color for the preview pane”.

    That’d be awesome. If what I’m saying is not as easy as it sounds, my apologies; it’s just a suggestion. Thanks for your dedication. Greetings from Mexico.

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