CesiumGS/cesium

ScreenSpaceEventHandler support for multiple KeyboardEventModifier keys at once

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#13,300 opened on Mar 13, 2026

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 (3 comments) (0 reactions) (0 assignees)JavaScript (3,324 forks)batch import
category - cameragood first issuetype - enhancement

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Description

Feature

Currently the ScreenSpaceEventHandler can only listen for mouse events with either Alt, Shift or Ctrl modifier keys.

It would be nice to be able to add a listener for when multiple modifier keys are held at the same time, like this:

const listener = () => {console.log("SHIFT and ALT are held")}

screenSpaceEventHandler.setInputAction(
  listener, 
  ScreenSpaceEventType.LEFT_DOWN, 
  [KeyboardEventModifier.ALT, KeyboardEventModifier.SHIFT]
)

Contributor guide

Research direction
Examine the ScreenSpaceEventHandler class in the Cesium source code, focusing on the setInputAction method where modifier keys are currently handled individually. The user requests the ability to pass an array of KeyboardEventModifier values. Review how the modifier state is checked during event dispatch and modify it to support multiple simultaneous modifiers. Check the comments in issue #13300 for any design considerations or maintainer feedback.
Tech stack
javascript
Domain
frontend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Understanding of Cesium event systemJavaScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65