OptionsSliderTemplate just appears to be inherited from UISliderTemplateWithLabels (which is in Era) but with a fixed size of 144 x 17 being the only difference.
It’s listed as being deprecated from retail (and presumably Cata) at some point.
Edit: but then again: https://github.com/Stanzilla/WoWUIBugs/issues/645
Yeah, that whole thing is just missing sadly. If it’s being deprecated, I wonder what they’re using the replace it with. I liked using the sliders because they didn’t create mysterious taint issues like the dropdowns did.
It appears UISliderTemplateWithLabels shouldn’t be deprecated (gone in any way), it’s just not listed in the .toc/xml includes. Hopefully Blizz. will add it back in “soon”.
You could copy the template to your own unique one until it’s added back or we know what’s going on. Bit of a hack but…
That would seem to indicate the template file is not missing from all game version .toc/xml files so presumably will return at some point to the missing one(s)
I’ve found the templates from the BlizzardInterfaceCode folder, but don’t have an example on how to incorporate them into an addon that is currently using them. Do you have a brief example or an addon doing this already?
Not an author, just trying to fix one that became broken with the last patch.
In the era addons .toc file, above the first line that ends with .lua or .xml, you could try adding
..\Blizzard_SharedXML\Classic\SliderTemplates.xml
If any other addon has done this that loads later, you will get a Duplicate Node error.
If/when Blizz adds it back in, you will also get a Duplicate Node error which will just mean, deleting the line you added from the .toc file.
This is a “personal” fix, not a fix for an addon to be published for others to download and use.