As I've pointed out in the MR, this only allows compositors to communicate to windows a scale factor (how many framebuffer pixels to send for each logical pixel

As I've pointed out in the MR, this only allows compositors to communicate to windows a scale factor (how many framebuffer pixels to send for each logical pixel of window size), but does not switch window sizes and subsurface positions/sizes from integer logical pixels to fixed-point logical pixels (rounded to integer physical pixels) or integer physical pixels. So Wayland is absolutely not ready for pixel-precise window resizing and positioning in the presence of fractional scaling.