[Bug]: Editor context menus have no background since the Monaco update after 3.7.0-rc.2 #523

Verification

• I have reproduced this problem on the latest stable or beta release, and checked the release notes and the existing issues
• Every statement in this report is one I verified myself. If I used an AI assistant to draft it, I checked each of its claims against the current code and documentation of this project

Duet Forum Discussion Thread

https://forum.duet3d.com/topic/39529/3.7.0-gcode-editor-possible-stylesheet-regression-in-context-menus-from-rc.2

Which Duet products are you using?

• None

Firmware Version

n/a, this is browser-side only

Duet Web Control Version

DWC 3.7.0

Are you using a Single Board Computer (RaspberryPi) with your Duet?

• Yes I use a SBC.

Please upload the results of sending M122 in the gcode console.

n/a

Please upload the content of your config.g file.

n/a

Links to additional info.

Upstream bug report: microsoft/monaco-editor#5511

What happened?

Expected result

The right-click menu in the G-code editor is drawn with the theme's menu background, border and shadow, as it was in 3.7.0-rc.2.

Observed result

Since 3.7.0 the menu has no background, border or shadow at all and its items float over the editor content. In dark mode the menu is barely readable. Chromium and Firefox are both affected, and so are the editor on the Explorer page and the G-code stream on the Job Status page.

Steps to reproduce

1. Open a file in the G-code editor.
2. Right-click anywhere in the editor.

This is a regression from the Monaco editor upgrade (0.56.0 to 0.57.0) that went in after 3.7.0-rc.2. Monaco 0.57 attaches the context menu's shadow host outside the editor element when fixedOverflowWidgets is set, and none of its theme colour variables resolve there. If no upstream fix lands before 3.7.1, DWC needs a workaround of its own.