Frameless is sort of a misnomer as they still have a frame. The glass itself does not have a frame.
I have not heard of many leaking issues and the ones I have heard of have been the clamp frame leaking due to bad installation, which is the same configuration as any RV window. The outside frame goes into the opening, the inside frame acts as a clamp when the screws are run in and tightened down. We have had them on the current and prior trailers we have owned, and never had a leak.
They are also referred to as "bonded" windows. Because the hinge extrusion and operator channel are bonded to the glass panel with an adhesive.
Here's the issues I have seen, had myself, or heard about.
1- There have been instances of the glass separating from the hinge extrusion due to adhesive failure and the glass panel falls off the trailer.
2- There have been issues of windows opening on their own while traveling down the highway, due to the cheap operator hardware used.
3- There have been issues with the operator arms breaking because they're cheap and chincy.
4- They only open about 3"-4" depending on the height of the glass, but it's easy to mod the cheap hardware to get them to open further to 6"-8", but your taking a chance with the cheap hardware. Once modded they really need treated with kid gloves.
5- Most, if not all are made by LCI, which goes a long way to explain why there are the first 3 issues.
"Now the Subaru with the โcoexistโ sticker on the back doing 68 mph passing a semi thatโs going 67mph in a 70 zone. Yeah Iโll slap the entitlement tag on them leaf lickers!" - Grit Dog - Warning, you may find the preceding offensive if you lick leaves.