Did you know that Windows remembers your current and historical display topography? Did you even know such a thing existed?

When writing my post about odd behavior introduced when using dual-screens with displays of differing pixel densities, a stray comment by Danchar stuck with me. He mentioned that Windows is great at remembering desktop topology. But what does this really mean?

Desktop topology here is desiring the metrics for your desktop environment. And the settings remembered go beyond a per-monitor basis, like remembering the resolution of your TV. When you have more than one monitor, your PC operates basically as if you had one single large desktop area, a grid, that spans the combined area of both displays. The only requirement is the screens are “touching” in this virtual space, providing a continuous grid as well as a place for the mouse pointer to pass between them. The monitors can share an edge, part of it, or just a corner.

By topology, I’m referring to the district layout of those physical displays in the virtual space. Windows remembers every unique combination of monitors, their settings, and the layout. This means the exact offset of one monitor to another for example, or the relative position (which edges are shared). And it does this for every unique layout wholly independently. For example, I have up to 3 displays on my Surface Pro 3 at times.

  • the built-in HD display
  • a low-res external Dell monitor (HDMI)
  • a low-res Westinghouse LCD TV (wireless display)

If I connect only the Dell to the Surface, the Dell monitor floats above and to the right of my Surface monitor, meaning the top-right corner of the Surface is the join between the two displays. However, if I then connect to the wireless display, it floats directly left (‘west’) of my Surface display, sharing the entire edge.

However if the Dell monitor is disconnected when I connect to the wireless display, it floats to the right of my Surface display.  That’s because the configuration of “Surface + Wireless” is a unique and wholly independent layout from “Surface + Wireless + Dell” configuration, and the relative position of Surface and Wireless don’t need to be the same in both configurations. Each topology is unique and distinct.

You can take it a step further by customizing which display is the primary in any given situation, but that comes with some downsides I’ve written about before. Chief among the issues is that because your primary monitor is used as the baseline for DPI scaling when loading your desktop environment, changing the primary monitor makes icons fuzzy and some content mis-sized sized you log off and back on (or at least restart the explorer.exe process).  For details and suggestions to overcome that annoyance, see DPI Scaling in HD Multi-Monitor Configurations.

And now, you know.