Multiple external monitors displayed incorrectly in Preferences > Sketches

Most appropriate sub-area of Processing 4?

Other (specify if possible)

Processing version

4.5.2

Operating system

verified on macOS 26.5.1 Tahoe

Bug description

When more than one external monitor is connected, the monitor layout shown in Preferences → Sketches → Run sketches on display does not match the actual display configuration.

Issues observed in the screenshot below (by @MickaelLafontaine):

• Seven displays are connected, but the UI shows only five. (using a monitor controller to connect to 4 displays from one input, appearing as a single display is expected)
• Two displays are shown as selected target display. Only one target display should be possible at a time.
• Multiple displays share the same labels (1 or 2) instead of each having a unique number (1 to 5).

Steps to reproduce this

1. Connect multiple external monitors.
2. Open Preferences → Sketches.
3. Look at the Run sketches on display monitor selector.

snippet

n/a

Additional context

Initially mentioned here: https://github.com/processing/processing4/issues/1426#issuecomment-4780421476

Would you like to work on the issue?

No, I’m just reporting the issue

Start at Preferences → Sketches and reproduce the issue with multiple external monitors connected on macOS. Inspect the Run sketches on display monitor selector and verify that the displayed layout matches the actual configuration, only one target display is selected, and each display has a unique label.