Glass paint pens that dye the glass but don't require baking? g?

OK so forgive me if this is the wrong place for this but I've just been on the hunt trying to find glass paint pens for my mum, the most common types are chalk, acrylic or oil based paint pens that I can find at least.

She had bought these glass paints probably over a decade ago in a local art shop and they lasted for a really long time, they stained the glass but she didn't need to bake the finished product for it to stay on the surface. (I'm presuming it was *better * if you did bake the product but these weren't for eating anything just decorative crafts and arting on glass.)

Would anyone be able to recommend good glass pens? She can't recall the brand name for the original pens she had, and about the only brand I've found that might similar are the oil based sharpie paint markers. I'm presuming these were oil based as I've used acrylic paint pens and they certainly don't absorb into surfaces.

Thanks for any responses