At least in stand alone mode while using a +% scaling mode, when I try to grab one of Halion’s edges with my mouse and drag it so the window is a bit taller or wider I’m getting a very strange behavior. Which ever way I’m trying to pull it the other dimension will change. For instance, when trying to widen the window the bottom edge of the window will begin to rise. This does not seem to be moving in a way that would suggest it is trying to maintain a particular ratio. If pulling a side edge the bottom edge will continue to go up and shrink the size of the window until it’s unusable.
I hope I’m explaining this satisfactorily. My mp4 screen shots are too big to upload.
For what it’s worth, this seems to work with the standalone HALion 7 on macOS, so apparently something Windows specific. Won’t help you, but might help to hunt down the bug (which I would report to Steinberg via Support)
I wonder if this is just the way the scaling works for now. The scaling isn’t infinite, but is quantized, so to speak, in 12.5% increments according to the announcement and release notes. Since this is the case, I would guess you are only supposed to use the menu or corner tab to resize, so height and width scale simultaneously in proportion.