Here is a picture

Hi Pennypond. I too was fascinated by this concept, especially as the size and configuration of my master bath space made it difficult to have a tub as well as a separate shower. The solution that let us have the features we wanted was a walk-through lipless shower to the bathtub. My bath was completed in April, and we are delighted so far.
It's a very long story, but the bottomline is that the really hard part was actually getting the concept and design implemented! It turns out that in my city of almost 1m people, this kind of custom work, especially in relatively small spaces, is still uncommon. Despite a detailed contract and initial assurances from my bathroom design/build firm (one of the top in the city), halfway through the contractor got cold feet and wanted to change the shower design and put in a shower lip. There were also arguments about the adequacy of the waterproofing, problems with the contractor's tiler and with a glass supplier which at the last minute decided they couldn't meet the glass design requirements. The information on this forum about waterproofing and design, and resources such as Houzz and Paul Anater's blog were invaluable.
My design is somewhat similar to the one in the picture. The tub is along a window wall, about 78" in length. I chose a deep soaker tub, but only 60" allowing a good size bench at the foot of the granite surround. The shower is along an exterior wall at the foot of the tub, so the bench is open to both the shower and the tub. The "wall" of the shower is a fixed floor-to-ceiling glass panel, plus a shorter hinged glass panel. The movable panel swings out 45 degrees, and swings in to almost parallel to the fixed panel. Although the shower floor area is not even 3 feet wide, the additional "arm space" over the tub, the long length and the open glass make it feel spacious. For us, it was worth the effort.

Feelicious. Providing to tub you choose has a tile flange integral to the ledge, it would be adaptable.

Feelicious, we have a walk through, no-lip shower with a tub on the other side. It works great. We don’t clean our tub after we shower. It is mounted in a deck, and gets a little water spray on the closest side, but our tub is waterproof, so I don’t see the problem. Do people clean their tubs after they shower IN the tub? Maybe so, but I don’t!

The squeegee their showers after every use. Or should. Hard to do that with a tub sitting there in the shower.

Well, I can’t see the photo above to be sure what the layout is. We do squeegee every time. The glass panel is on the north side of the shower and the tub is on the south side, with a big window. It isn’t freestanding though— that layout would seem to take a lot of space to clean around!