This isn’t a bug. 
While it would be possible to set an offset for images that use the same image size and aspect as the background, we can’t assume that every image will do so. The original intention was to enable the use of existing MAME cabinet glass art, which vary in size and aspect.
The same goes for any layer that is set to scale with the tube or bezel.
Thankfully, you only have to scale and position one layer and the rest can follow it.
Got it… thanks. Is there a key combo or setting that will allow you to move the slider settings faster while you are in the parameters screen (using arrow keys). Some of these can be pretty slow.
If you press Enter or the “A” button on your controller, while focusing on the parameter, you can use the trigger buttons or the left and right arrow keys to page down and up.
Perfect… that’s going to help.
It would be nice if the shader system allowed us to type in values.
I was happy the day I realized I could use the arrow key and see the results in real time instead of going into each parameter and scrolling up and down to the value I wanted. 
Oh… I see. I thought you meant enter as a combo with the arrow buttons to slide the values more quickly.
I would be great if you could hold a key, then press an arrow button to move the slider faster and see it in real time.
The step value is defined in the shader and AFAIK there is no way to use a hotkey to increase it.
Understood. Thanks for all the help.
What I do is make big jumps using the page down method, then fine tune in real time after I get it close.
Thanks for the feedback Duimon. You will see in the screenshot that I’ve gotten pretty close.
So I am using one of your Sega Dreamcast presets for the Atomiswave games since I’m also using the Flycast core here. But you can see that the Sega logo from your dreamcast night shader is visible still. Also, in the txt you will see I’m using your bezel but it’s pointing to Cyberlab’s death to pixels shader although I assume that should not make a difference. I’ve added the path to the Atomiswave png and the line HSM_BG_LAYER_ORDER = “6.000000” as well.
What final steps should I take to ensure it looks just like it does here, without the Sega logo and with the exact same border as shown in orionsangel’s vid. Assuming it is possible of course. Otherwise I’m fine using the border you see in my screenshot, give it a darker huge, but with the Sega logo removed. Oh yeah, finally the Sammy logo looks squished, unreadable basically. Not sure why it is doing that.
I assume I can also add a tilt and even change the pinkish color of the main portion of the bezel?
Thanks.
That would be an incorrect assumption. Some of his presets use integer scale so cannot be finely tuned to line up with the edge of the hole. You will need to use one that uses non-integer.
If you just want the bezel to tilt inside the whole the you are correct. If you want the art to tilt with it you are out of luck.
Additionally, Cyber’s presets may get funky looking using tilt. You are on your own figuring out how to fix any mask related funkiness.
As far as the color goes, unless you can separate the logo and trim around the hole to a separate layer, it will get funky looking as you adjust the HSV to change the color.
Also it appears you are using my [Custom_Bezel_2] preset which is not needed because you intend to hide the frame behind the art.
Honestly, in this situation it makes no sense to use my preset. My presets are built to work with my image layers and you wont be using them. Just load Cyber’s preset and save a content directory preset, then make your changes in there. This will solve most of your issues.
I love this new version. This is getting better and better 
HSM_Mega_Bezel_Examples V1.4.0_2023-01-12
Changes:
Go to the first post here for links to the package and install instructions. Please make sure to read the install & setup instructions
Neo Geo Preset without and with Reflection Mask
P3st Terminator 2 Lightgun example
P3st PlayChoice Lightgun example
I have the latest version but still in the information I get the following: V1.7.0_2022-12-21
Where do you go to look for the version information?
If you are seeing this, then it is definitely not the latest version. I just checked the package on Github and it is the new version V1.8.1_2023-01-11.
This update has not been pushed to the main Libretro repo yet, so perhaps you only updated through Retroarch’s Update Slang Shaders action?
My error in downloading from GitHub and then updating from RetroArch. Now if it’s ok
i just made an mask for the glass preset to maybe get reflections on the cab without realising you can´t set device images etc. with the glass presets ^^
maybe i need i thrown together presest as an test subject one day
Yeah, although the glass preset is just a specialization and simplification of the full preset like ADV or STD.
If you drop the same parameter values from the base glass preset on top of the STD you will get something similar to glass. It is basically just a very very large bezel and adjusted reflection parameters.
You can certainly play with the reflection mask with this but without procedural controls its going to be kind of rigid.
To get something for the cab reflections (wings, speaker & control panel) I need to add some more features to help control reflection outside the bezel area, with falloff and brightness control per area, and ways to control how to define the different areas.
That is what I did to get the Glass variations before I set them to use the Glass presets.
