Use two scaling factors instead of one

Most displays come in high pixel densities more than 96dpi.(up to 150DPI for HD displays, up to 300 DPI for 4K displays) However, some applications assume pixel density is fixed and use raster images and raw mouse data for UI elements. They either look too small or fail to track mouse movements correctly. I request splitting the DPI control into two fields:
Renderer DPI: HiDPI-unaware application rendering target.(default=96)
Resultant DPI: Final image will be scaled into that DPI.(this needs to be autodetected)
There enters a scaling factor. = sqrt (dpi_resultant/dpi_renderer)
High DPI unaware applications and its mouse tracking will be scaled for actual DPI by the scaling factor instead of scaling the entire desktop if this feature were implemented. Therefore, even looking ugly by scaling twofold, there will be no UX problems in high-DPI unaware applications. High DPI aware applications will directly be rendered for the actual DPI.