[BUG] Open RemoteApp will cause Server PC's theme change

[chuwza]

Hi, I deployed remoteapptool on a freshly installed Windows 10 PC

Of course, Windows 10 needs install this crack patch (rdpwrap) at the first to support multiple users rdp.

And I generated the test.rdp file for notepad++(Everything is default except ip),than when I open test.rdp on another computer, Notepad++ run OK.

But Server Windows 10 PC changed its theme! This is so strange!

You can see it in the video.

Screenbits.2025-05-18_210025.mp4

At first, the Server PC's theme is light mode, but when I open notepad++, the Server PC's theme changes to dark mode!

Moreover, this light/dark mode switching is not regular, sometimes remoteapp turns light mode into dark mode, and sometimes it turns dark mode into light mode.

And interestingly, when I open test.rdp using RD Client for Android, it doesn't trigger this. It only occurs when I open test.rdp on a Windows computer!

Screenbits.2025-05-18_213013.mp4

To troubleshoot and thus prove that it's a remoteapp issue, I deployed a fresh Windows 10 PC via VMware without installing any additional software (such as video), The remoteapp tool was deployed on this new PC

I've tested this many times on new PC and it happens 100% of the time and I don't understand why. At first I thought it was a third party app interfering, but it happens on new PCs too!

If you have two Windows 10 PCs, you can try it and I guarantee 100% reproduction!

Personally, I think this is a bug in remoteapp, so could you please fix this bug?

[MrBrianGale]

My opinion, this is not a remote app bug but likely a bug in rdp wrap OR in your system setup (client machine, server machine, rdp application, etc.) remote app tool doesn't explicitly define a light/dark mode so it shouldn't be changing anything. Plus if it was a bug due to this tool, it would be reproduced across as clients (windows, Android, Mac, Linux, etc). Since this only happens with windows, it is very likely due to the crack you installed which I thinking it's actually against Microsoft terms of service...

[chuwza]

My opinion, this is not a remote app bug but likely a bug in rdp wrap OR in your system setup (client machine, server machine, rdp application, etc.) remote app tool doesn't explicitly define a light/dark mode so it shouldn't be changing anything. Plus if it was a bug due to this tool, it would be reproduced across as clients (windows, Android, Mac, Linux, etc). Since this only happens with windows, it is very likely due to the crack you installed which I thinking it's actually against Microsoft terms of service...

Hi, thank you very much for your reply.

You think the cracked patch cause problem. Well, so I tested on Windows Server without the cracked patch and found that the theme still be changed.😥

Screenbits.2025-05-18_225735.mp4

As in the video, when I start test.rdp on another PC, the Settings program on the right side changes to dark mode. compared to Windows 10, the situation is even more confusing, the left explorer and the taskbar don't change color.

I found that this is only triggered by adjusting the Settings to Perconalizaiton-Colors and, again, sometimes it is the light mode changes to dark mode, and sometimes dark to light.

I wasn't sure, but now I'm even more sure that it's a remoteapp problem, because the strange phenomenon also happens on a fresh install Windows Server

[MrBrianGale]

Based on how this tool works (creates an entry in the registry to run the app and generate an rdp file), there is no way for the app to change the theme. The most likely culprit is either you modified the rdp file after generation, you made a setting change before rdp file generation to cause this, or the client rdp application you are using is sending weird requests to the server.

This tool uses the same methods Microsoft does, just in a more user friendly way and allows it to be run on a non server edition of Windows.

What you could do is try editing the rdp file to remove done of the options to try to find the offending option (if one exists). Otherwise, I feel this is likely caused by your environment (client machine settings, server settings, etc). Heck, it could when be a licensing thing but Microsoft to encourage licensing. Windows server requires a user cal in order to rdp to it and this includes remote app usage. Windows desktop doesn't support multi user so circumventing that may trigger something like this annoy users into buying licenses. I've not heard of that but no reason they couldn't do it. Or if it is a pirated copy (not saying it is, just using it as an example), a system file may have been modified that doesn't impact most users but does impact remote app users...

[chuwza]

Based on how this tool works (creates an entry in the registry to run the app and generate an rdp file), there is no way for the app to change the theme. The most likely culprit is either you modified the rdp file after generation, you made a setting change before rdp file generation to cause this, or the client rdp application you are using is sending weird requests to the server.

This tool uses the same methods Microsoft does, just in a more user friendly way and allows it to be run on a non server edition of Windows.

What you could do is try editing the rdp file to remove done of the options to try to find the offending option (if one exists). Otherwise, I feel this is likely caused by your environment (client machine settings, server settings, etc). Heck, it could when be a licensing thing but Microsoft to encourage licensing. Windows server requires a user cal in order to rdp to it and this includes remote app usage. Windows desktop doesn't support multi user so circumventing that may trigger something like this annoy users into buying licenses. I've not heard of that but no reason they couldn't do it. Or if it is a pirated copy (not saying it is, just using it as an example), a system file may have been modified that doesn't impact most users but does impact remote app users...

Hi, thanks for your help, regarding what you think it is:

client machine settings, server settings, etc, a system file may have been modified

I can strongly refute it because I used a freshly installed server machine (Windows Server/10) and a freshly installed client machine (Windows 10) and this problem still occurs! And I assure you that I have not changed any .rdp settings.

Screenbits.2025-05-19_093818.mp4

I even cleared the .rdp settings. (test again)

it could when be a licensing thing

I didn't even activate either machine!😂

I think that's enough to show that it's not my personal problem.

You can absolutely create two virtual machines using VMware and try it and you'll see what I'm talking about. For now, I can guarantee that this phenomenon is 100% reproducible.

Of course, I'm not saying that it's necessarily a problem with remoteapptool, it's possible that the problem comes from what you said at the beginning: Microsoft 's rdp and the program.

[MrBrianGale]

If you give me a few days, I can spin up some vms (azure as I have nothing that can run VMware) and try to replicate. Just to confirm, client and server are base installs with no additional configuration on the user accounts? Just want to try to replicate this as I have not heard from anyone else that this is an issue.

As for clearing the rdp settings, I meant in the .rdp file. Some of the things in there are optional.

[chuwza]

If you give me a few days, I can spin up some vms and try to replicate.

Hi, thanks for being willing to try. Please note, however, that whether the server machine changes from dark to light or light to dark is random. If you fails to reproduce the strange phenomenon, then you need to pre-switch the theme to another color.

As shown in the video, at first when I set the server machine to dark mode, the strange phenomenon didn't appear🤔. And when I set the server machine to light mode, the strange phenomenon appeared ......🤣

Screenbits.2025-05-19_103649.mp4

Just want to try to replicate this as I have not heard from anyone else that this is an issue.

I don't get it either, maybe they thought the phenomenon was hard to describe so gave up issue?

As for clearing the rdp settings, I meant in the .rdp file. Some of the things in there are optional.

Okay, based on your correction, I'll try it again

[jackbuehner]

Just jumping in here to say that this may be something weird going on with Windows. I have something similar happening (the accent color changes) with my RemoteApp RDP files, and those were not created with this tool. I do not remember when this first started happening, but I know it is within the last year.

[chuwza]

Just jumping in here to say that this may be something weird going on with Windows. I have something similar happening (the accent color changes) with my RemoteApp RDP files, and those were not created with this tool. I do not remember when this first started happening, but I know it is within the last year.

Ok, thank you very much for the information! Windows really sucks.😂😁

[jackbuehner]

I think I found what is going on.

MS-RDPERP allows transmitting accent color as a TS_ACCENTCOLOR structure in RAIL_SPI_ACCENT_COLOR and dark/light mode information in RAIL_SPI_SYSTEM_USES_LIGHT_THEME and RAIL_SPI_APPS_USE_LIGHT_THEME (scroll to the bottom of TS_RAIL_ORDER_SYSPARAM)

These options were added in Windows 11 24H2 and Windows Server 2025 (based on 24H2). From the limited testing I have done, mstsc.exe seems to properly transmit the accent color and dark mode information when the client and server are both at least 24H2. However, with earlier versions, this is less reliable. For example, when I connect using 23H2, the titlebar accent color and dark mode status are sometimes properly set, but the accent color is always wrong.

I don't know why older windows versions are sending/receiving garbage values for RAIL_SPI_ACCENT_COLOR. Perhaps code that works only on 24H2 made its way into older versions as part of security updates.

The specification changelog calls this the accent color accessibility feature. I also do not know if there is any way to disable the feature, and this term only appears in the specification.

I am also confident that this is an issue with Windows, not RemoteApp Tool.

[jackbuehner]

It seems like the terminal server may be getting the titlebar/border color from the last 24H2 client that connected.

1. 24H2 Teal -> Server Teal
2. 23H2 Purple -> Server Teal
3. 24H2 Brown -> Server Brown
4. 23H2 Purple -> Server Brown

I haven't seen a consistent pattern for the accent color. I have received light red, dark red, very dark red, and yellow.

[chuwza]

Okay, I understand. Anyway, thank you very much for your work.👍 At least we know why this strange problem exists!😆

[jackbuehner]

I am in contact with a Microsoft Engineer, who has confirmed that this is a known issue. The devs plan to have a fix deployed in the next windows feature updates. The devs want to backport the fix, but they need to have a written statement from a customer describing the business impact of this issue (number of users this issue may affect and how) before the team can push for the backport.

To anyone watching this issue: please send me an email if you can provide a statement. Send to (my first name) @ (my github username) .com

[manprost]

BTW, this appears to have been fixed with the December Windows updates, at least on my Windows 11 LTSC 24H2 (server and client). Thank you @jackbuehner for clarifying the issue.