How can I move a streamed desktop to one side of the target screen?

Use a source with a narrower aspect ratio than the target, preserve its proportions, and choose left or right alignment. The unused space gives the stream room to move sideways. If the source already fills the target width, there is no spare horizontal space.

For example, to leave a black area on the right:

  1. Create a virtual screen with a taller, narrower aspect ratio than the receiving display.
  2. Stream that virtual screen to the receiving display. Streaming and its alignment options require Pro.
  3. Leave 1:1 Pixel Mapping and Free Aspect Ratio off so the image fits the target while preserving its proportions.
  4. Under Horizontal, select the left-alignment icon.

The whole source desktop remains visible, aligned to the left, with unused space on the right. Adjust the virtual screen's aspect ratio to change how much space remains. This changes how the desktop is presented. It does not alter the optics of a wearable display.

To leave an unused band at the bottom, use a shorter, wider source aspect ratio and select top alignment under Vertical instead. Keep your working windows on the virtual desktop being streamed. This is a streamed-desktop workaround, not a system-wide exclusion zone: macOS can still place windows on the physical target’s own desktop. It requires BetterDisplay and the stream to remain running.

On Apple silicon, native display underscan is a separate possibility when you want the whole desktop to occupy less of a large screen. Force-enable underscan slider in the display’s Device Control > Image Adjustment Settings… can expose that native slider, but cannot make an unsupported connection implement it. The forced option may have no effect or cause system issues. It is separate from stream underscan. See Device Control before trying the forced option.

If Underscan keeps leaving a margin on the aligned edge, return it toward 100% and use Zoom to size the image before alignment. Zoom changes the stream frame used for alignment, while underscan insets the image within that frame. Compare the result as you adjust them. Reducing Zoom can leave space on the opposite side when you align the stream to an edge.

For unused borders around all sides, use a smaller virtual source and enable 1:1 Pixel Mapping, keeping the stream centered. Compare the source’s actual rendering dimensions with the target’s pixels, especially for HiDPI modes. This can keep content away from damaged screen edges, but streaming can add latency and does not repair discoloration. It also does not provide a custom, blended color correction limited to the damaged margin.

The macOS scaling explanation distinguishes desktop size, rendering pixels and physical output.

See Streaming for sizing and alignment, and Virtual Screen settings for source dimensions.

Follow the damaged-screen tutorial to fit a virtual desktop into a usable panel rectangle.