Extensions, UC.JS/UC.XUL Scripts, CSS Stylesheets and Custom Buttons for UXP browsers - Corrections, modifications, adjustments, and recommendations

[GH0st]

On 1/10/2026 at 1:47 PM, Amigafever said:

Most probably the "Legacy" version, as compared to the WebExtension

Yes, This version, I mean the Legacy version rather then the newer version Gorhill works on now.

[VistaLover]

14 hours ago, GH0st said:

I mean the Legacy version rather then the newer version Gorhill works on now

No offence meant, really, but I don't see the point of your query ; you want a comparison between apples and oranges, when, in practice, the XUL ("legacy") and the WE (MV2) CAN'T be really compared, due to them targeting different platforms/web engines; this thread here is about the XUL variant, which is the only one supported by the (official) UXP-based browsers; actually, roytam1's St52/St55 have retained some rudimentary support for fx-52 level Web Extension APIs, but if you plan on installing there the WE-variant(s) of uBO from ca. 10yrs ago, then you should ditch that idea right away; those ancient WE versions are no match for the web of 2026...

TL;DR: UXP-based browsers don't support at all the what you called "newer version Gorhill works on now"  ; you are limited to installing the XUL variant; any "academic" comparison is totally moot  in this context (similarly, recent Firefox, and its forks, do not support the XUL-variant, only the WE-variant; and currently, that requires fx-115esr and later) ...

[AstroSkipper]

Hello everyone!  Today, I changed the title of this thread. My new focus in this thread is on UC.JS loaders and the associated UC.JS scripts. I stopped using custom buttons with the 'Custom Buttons’ extension quite some time ago. UC.JS scripts are far more powerful than the legacy custom buttons. You have full access to the browser’s native (Vanilla) JavaScript. Since the beginning of last year, I have converted all my beloved, self-written custom buttons into UC.JS scripts and written many new scripts myself, initially targeting Mypal 68. Since last month, I began porting them to the New Moon 28 and Serpent 52 browsers. In the meanwhile, I have completely removed the Custom Buttons extension, including all custom buttons, from these browsers. I have reduced the use of other extensions to an absolute minimum and started to replace all missing functionality by UC.JS scripts. What interests me personally here is whether you have installed any UC.JS loaders in New Moon 28, Serpent 52 or Pale Moon, and if so, which ones, as well as how extensively you use UC.JS scripts in general. 

Edited May 7 by AstroSkipper
Update of content

[Amigafever]

This is quite an interesting area, the uc.js stuff. I don't use any of the above browsers but I'd still love to see your efforts and new scripts.

In general, I prefer to avoid using them since they are a bit hacky and cumbersome to handle, but the power and potential of these cannot be ignored.

[AstroSkipper]

On 5/7/2026 at 12:56 AM, Amigafever said:

This is quite an interesting area, the uc.js stuff.

I can confirm that, and more than that. 

On 5/7/2026 at 12:56 AM, Amigafever said:

they are a bit hacky and cumbersome to handle

However, I can't confirm that.  They are easy to handle and can be directly modified at any time. I additionally use a UC.JS/UC.XUL script manager to get full control of them and to activate or deactivate them if desired. You always see the starting order when it is of the utmost importance. At the moment, I am running 20 UC.JS/UC.XUL scripts in New Moon 28 as well in Serpent 52 without any errors. Most of them are ports from scripts I originally created for Mypal 68/74/78 and indeed self-created from scratch. You can use these scripts to retrofit almost anything with pinpoint accuracy.  Retrofitting all of this with extensions is far more labour-intensive and would consume an much larger amount of resources. In any case, my browsers are in perfect condition, so to speak. 

Edited May 21 by AstroSkipper

[exogenesis]

Custom Buttons MyPal SuperStop I know it works I know it is good and does stop them dead. Needing this now more for Newmoon28 SSE

 

I read you are changing these to be better I'm not sure where you are at in development or have completed that. Is there this update archive pack available of all the Custom Buttons to download with new uncomplicated install instructions for NewMoon28. I have downloaded custom_buttons-0.0.5.8.9-fixed8-signed.xpi it's date is 2018

 

Has a look in the archive [ \custombuttons.jar\content\custombuttons\ ] is SuperStop in or one if these renamed. Or is there an extension that is it SuperStop that works with newmoon28 and that works like SuperStop to kill the page dead when needed with delay of high CPU that many extensions have a problem with.

 

JustOff github.io there are his 30 extensions I guess you may have got these to try yourself. Do have you a link of all of these zipped up

 

 

 

 

 

[AstroSkipper]

@exogenesis Did you really read my last articles carefully?  I don't think so.  Here is my comment about the legacy custom buttons and what I am doing at the moment:

On 5/6/2026 at 9:11 PM, AstroSkipper said:

Hello everyone!  Today, I changed the title of this thread. My new focus in this thread is on UC.JS loaders and the associated UC.JS scripts. I stopped using custom buttons with the 'Custom Buttons’ extension quite some time ago. UC.JS scripts are far more powerful than the legacy custom buttons. You have full access to the browser’s native (Vanilla) JavaScript. Since the beginning of last year, I have converted all my beloved, self-written custom buttons into UC.JS scripts and written many new scripts myself, initially targeting Mypal 68. Since last month, I began porting them to the New Moon 28 and Serpent 52 browsers. In the meanwhile, I have completely removed the Custom Buttons extension, including all custom buttons, from these browsers. I have reduced the use of other extensions to an absolute minimum and started to replace all missing functionality by UC.JS scripts. What interests me personally here is whether you have installed any UC.JS loaders in New Moon 28, Serpent 52 or Pale Moon, and if so, which ones, as well as how extensively you use UC.JS scripts in general. 

Please note the underlined sentences! And BTW, here is no package of custom buttons or whatever it is you're on about. Since the beginning of 2025, I am a UC.JS script programmer. I develop scripts for use in Mypal 78, Serpent 52 and New Moon 28. And to say it again clearly, custom buttons and its extension is history for me. 

10 hours ago, exogenesis said:

Custom Buttons MyPal SuperStop

SuperStop is not a custom button but a webextension. You can get it here: https://addons.mozilla.org/en-US/firefox/addon/superstop/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search
If you're still interested in the old custom buttons and you want to stop all GIF animations, then have a look at my article: 

 

Edited May 22 by AstroSkipper

[AstroSkipper]

UC.JS Programming

Given the feedback – or rather the lack of it  – I assume that either nobody in New Moon or Serpent is using UC.JS/UC.XUL scripts, or that there is a massive lack of interest in this topic , or simply the usual passivity. 

What is so special about UC.JS/UC.XUL scripts in these two browsers?

If you search for such scripts online, you’ll find that most were created for newer versions of Firefox, i.e. Firefox 57+ or even Firefox 68+. And the situation is just as dire when it comes to compatible script loaders. If you’re now thinking, ‘But there is an extension called userChromeJS in the form of an XPI file’, then you’re right. But the latest version, 2.0, dates from 2010 and is far too old to load all modern scripts, meaning the functionality of this loader in New Moon or Serpent is rather limited. It was adequate back then, but no longer in this day and age. Most users install a varying number of extensions to add missing features. There are still a few current and well-maintained ones, but most are ancient, no longer developed versions. They generate numerous error messages, no longer function fully, consume resources and, in the worst case, cause incompatibilities. I’ve left all that behind me. The loader I use, which has been additionally patched by me, is much more up to date. It is implemented in exactly the same way as in Mypal 78. So no longer in the form of an extension. UC.JS/UC.XUL scripts consume significantly fewer resources and can provide precisely the functionality required without installing any extra bloatware. And their access via the browser is virtually unlimited.

What are the specific challenges involved in creating UC.JS/UC.XUL scripts in New Moon or Serpent?

Although Serpent 52 is also based on the very old Firefox version 52, it is nevertheless considerably more modern than New Moon 28. This browser already features the excellent CustomizableUI interface. At the time, Moonchild Productions decided not to integrate the CustomizableUI interface, introduced in Firefox 29+, into Pale Moon. Consequently, all widgets and toolbar buttons from UC.JS scripts in New Moon 28 must be created differently, i.e. in a completely basic, ‘old-school’ manner. This is a major problem. Such buttons are injected into the DOM very late by the script loader and are then regarded as foreign by the browser. They are not really managed by it. Therefore, the developer of UC.JS scripts must also take care of this. In Serpent 52, this is much easier, as CustomizableUI is fully present, albeit not up to date. Furthermore, of course, some things always need to be adapted specifically for each browser. Scripts that work in Mypal 68/74/78 usually do not run in Serpent 52 or, quite possibly, in New Moon 28. And the scripts in Serpent 52 do not run straight away in New Moon 28 either, for a variety of reasons.

I’ve now overcome every obstacle. Since early 2025, I’ve single-handedly written countless scripts for Mypal 68/74/78, and ported them first to Serpent 52 and then even to New Moon 28. My script loader, all my scripts and even the extensions I use no longer produce a single error in the browser console. To achieve this, I had to fix a few extensions that haven’t been maintained for a long time, such as Violentmonkey, Navigation Bar Enhancer and Toolbar Buttons. I have now expanded my one man team to include an AI that I have trained specifically for this purpose. All this means that you can use UC.JS and even UC.XUL scripts in New Moon or Serpent just as you would in, for example, Mypal 78. 

So, that was my first report on this topic. Enjoy reading! 

Edited May 23 by AstroSkipper

[exogenesis]

On 5/22/2026 at 12:20 PM, AstroSkipper said:

@exogenesis Did you really read my last articles carefully?  I don't think so.  Here is my comment about the legacy custom buttons and what I am doing at the moment:

Please note the underlined sentences! And BTW, here is no package of custom buttons or whatever it is you're on about. Since the beginning of 2025, I am a UC.JS script programmer. I develop scripts for use in Mypal 78, Serpent 52 and New Moon 28. And to say it again clearly, custom buttons and its extension is history for me. 

SuperStop is not a custom button but a webextension. You can get it here: https://addons.mozilla.org/en-US/firefox/addon/superstop/?utm_source=addons.mozilla.org&utm_medium=referral&utm_content=search
If you're still interested in the old custom buttons and you want to stop all GIF animations, then have a look at my article: 

 

No I didn't read all of what you wrote, and I have tried a few times to read over the months. In future for your posts I will copy them to a notepad, and space out you have written, then easy to read and digest.

 

Extensions they have a bad habit on waiting on the CPU when the CPU is Maxed. It does seem that some scripts are not so effected by CPU maxed and can react faster. I do realize you are in the creative process of UC.JS/UC.XUL scripting UC.JS/UC.XUL scripts. I do have hope these scripts will  be the type that can also cut through the CPU Max staying high after the web page loads scripts.

 

SuperStop for GIFs - I am not using it for any GIFs or have any plans to (unless I need to - not so far). The Purpose for using this script is only to stop the CPU Maxed after the web page has loaded. So with one or two left mouse button clicks it does stop a page loading dead. Which means it takes the CPU from maximum high 100% down to 0%-2% CPU instantly and there the CPU remains at 0-2% which is the normal background for this CPU with the OS running, when it is at idle.

 

Hope for the same results with NewMoon28

 

 

[AstroSkipper]

1 hour ago, exogenesis said:

SuperStop for GIFs - I am not using it for any GIFs or have any plans to (unless I need to - not so far). The Purpose for using this script is only to stop the CPU Maxed after the web page has loaded. So with one or two left mouse button clicks it does stop a page loading dead. Which means it takes the CPU from maximum high 100% down to 0%-2% CPU instantly and there the CPU remains at 0-2% which is the normal background for this CPU with the OS running, when it is at idle.

 

Hope for the same results with NewMoon28

Once again. There is no SuperStop for New Moon 28. You have to create a script with same functionality or combine different, already existing methods via extensions, custom buttons, scripts or CSS stylesheets to get a similar effect. One of them is ToggleGifAnimations.

[AstroSkipper]

15 hours ago, AstroSkipper said:

16 hours ago, exogenesis said:

SuperStop for GIFs - I am not using it for any GIFs or have any plans to (unless I need to - not so far). The Purpose for using this script is only to stop the CPU Maxed after the web page has loaded. So with one or two left mouse button clicks it does stop a page loading dead. Which means it takes the CPU from maximum high 100% down to 0%-2% CPU instantly and there the CPU remains at 0-2% which is the normal background for this CPU with the OS running, when it is at idle.

 

Hope for the same results with NewMoon28

Once again. There is no SuperStop for New Moon 28. You have to create a script with same functionality or combine different, already existing methods via extensions, custom buttons, scripts or CSS stylesheets to get a similar effect. One of them is ToggleGifAnimations.

I made a little research.In fact, there is an earlier legacy version of SuperStop by the same author which therefore can be installed in New Moon 28. But it’s rather poor. It only uses the browser’s built-in BrowserStop() function, which merely stops the current tab from loading. This version, SuperStop 0.1, can be found in the Classic Add-ons Archive (caa). But, as I said, it can only do a fraction of what the later webextension, SuperStop 0.6, does, which stops active WebSocket connections, JS timers, XMLHttpRequests, and any animated images and videos.

Edited May 24 by AstroSkipper