A BrowserSetting object which determines whether the browser's context menu is shown on the mouseup event or on the mousedown event.

Its underlying value is a string that may be either "mouseup" or "mousedown".

The default value is "mouseup" on Windows, and "mousedown" on macOS and Linux. Assigning to it on Windows has no effect - the setting is only designed to allow the context menu to be opened on mouseup instead of mousedown, not the inverse.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxOperaSafariFirefox for Android
contextMenuShowEventChrome No support NoEdge No support NoFirefox Full support 59Opera No support NoSafari No support NoFirefox Android Full support 59


Full support  
Full support
No support  
No support


Set the setting to "mouseup":

function logResult(result) {
  console.log(`Setting was modified: ${result}`);

browser.browserSettings.contextMenuShowEvent.set({value: "mouseup"}).