Desktop Mode: Spectacle region selection causes DisplayPort signal loss on official Steam Deck Dock (regression)

Your system information

• Steam Deck model: LCD (512 GB launch model)
• Steam client version:
  • Steam Version: 1782861641
  • Steam Client Build Date: Tue, Jun 30, 2026 01:24 UTC
  • Steam Web Build Date: Wed, Jul 1, 2026 00:10 UTC
  • Steam API Version: SteamClient023
• SteamOS version: 3.8.16 (Build 20260716.1)
• Opted into Steam client beta?: No
• Opted into SteamOS beta?: No (Stable)
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

After updating to SteamOS, can't be sure of the version, just that this did not happen 1-2 months ago and it started happening around the time the steam machine was closing to launch, Spectacle's interactive screenshot mode causes my external monitor to briefly lose its DisplayPort connection whenever the region selection overlay opens and again when it closes.

This is a regression. I have used the same Steam Deck, official Steam Deck Dock, DisplayPort cable and Gigabyte G34WQC monitor as my primary desktop setup since the official dock was released, and this behaviour did not occur before the recent major SteamOS update.

When Spectacle enters region-selection mode, the monitor goes black for approximately 1–2 seconds. The monitor then displays its DisplayPort connection/resolution OSD (the same OSD shown when a DisplayPort signal is disconnected and reconnected), after which the region-selection overlay appears.

When the region selection is completed or cancelled, the monitor again loses the DisplayPort signal for approximately 1–2 seconds before returning to the desktop.

The issue is fully reproducible.

Expected behaviour:

Launching Spectacle's region-selection overlay should not interrupt the DisplayPort connection or cause the external monitor to lose signal.

Actual behaviour:

The DisplayPort connection is briefly lost both when entering and leaving Spectacle's interactive region-selection mode.

Hardware configuration:

• Steam Deck LCD (512 GB launch model)
• Official Steam Deck Dock (firmware kept up to date, exact version unknown)
• Monitor: Gigabyte G34WQC
• Connection: DisplayPort
• Resolution: 3440×1440
• Refresh rate: 60 Hz
• Desktop Mode (Wayland)
• External monitor only (built-in display disabled)

Additional observations:

• Pressing the Print Screen key reproduces the issue every time.
• Launching spectacle manually also reproduces the issue.
• Running spectacle --background --fullscreen does NOT reproduce the issue.
• Fullscreen screenshots are captured successfully without any DisplayPort signal interruption.
• This suggests the issue is specific to Spectacle's interactive region-selection mode rather than screenshot capture itself.

Steps for reproducing this issue:

1. Boot the Steam Deck into Desktop Mode.
2. Connect an external monitor to the official Steam Deck Dock using DisplayPort.
3. Launch spectacle (or press the Print Screen key).
4. Observe that the external monitor loses the DisplayPort signal for approximately 1–2 seconds before the region-selection overlay appears.
5. Complete or cancel the region selection.
6. Observe that the external monitor again loses the DisplayPort signal for approximately 2–3 seconds before returning to the desktop.

Start by reproducing the issue in Desktop Mode with the listed dock, DisplayPort monitor, and Wayland setup, using spectacle or Print Screen. Compare interactive region selection with spectacle --background --fullscreen, then trace the display behavior around entering and leaving the overlay. Done means region selection no longer interrupts the external DisplayPort signal.