Detecting shift/command click on Chrome browser action button - google-chrome-extension

Question

Is it possible to detect a shift-click or command-click on a browser action button in the chrome bar?
For example, the following code does not work:
chrome.browserAction.onClicked.addListener(function(e) {
console.log(e.shiftKey) // is undefined
});

Answer 1

I've found a way to accomplish this. In my case, I needed to detect a ctrl-click and a ctrl-alt-click event on the toolbar icon.
Apparently the background script cannot capture keyboard events, but the content script can. So I set an event listener in the content script to listen for ctrl and alt keypresses and send a message to the background script. As it happens, the keydown event has boolean properties for ctrlKey and altKey built in so I did't have to implicitly check the value of the keypress. In your case, can use the shiftKey property.
content.js
window.addEventListener('keydown',function(event){
if(event.ctrlKey){
chrome.runtime.sendMessage({type: 'ctrlPressed'}, function(){});
}
if(event.altKey){
chrome.runtime.sendMessage({type: 'altPressed'}, function(){});
}
});
window.addEventListener('keyup',function(event){
chrome.runtime.sendMessage({type: 'keyup'}, function(){});
});
background.js
var ctrlPressed = false;
var altPressed = false;
chrome.runtime.onMessage.addListener(function(request, sender, sendResponse){
switch(request.type){
case 'ctrlPressed':
ctrlPressed = true;
break;
case 'altPressed':
altPressed = true;
break;
case 'keyup':
ctrlPressed = false;
altPressed = false;
break;
}
});
Now my chrome.browserAction.onClicked.addListener can detect a click, double-click, ctrl-click, and ctrl-alt-click. (With just a little more code I could also detect ctrl-double-click and ctrl-alt-double-click.) The only caveat is that the active tab must have focus to capture keypresses. The window.focus() line at the end of the routine should handle that.
background.js
// Listen for toolbar icon clicks
var clickCnt = 0;
chrome.browserAction.onClicked.addListener(function(tab){
clickCnt++;
if(clickCnt > 1){
console.log('Double click detected');
clickCnt = 0;
clearTimeout(timer);
}else{
if(ctrlPressed){
if(altPressed){
console.log('ctrl-alt-click detected');
}else{
console.log('ctrl-click detected');
}
}
timer = setTimeout(function(){
console.log('Single click detected');
clickCnt = 0;
}, 250);
}
window.focus()
});

Answer 2

No, it's not provided by the API. You can't detect modifiers, or different mouse buttons.
Chrome API events are not DOM events, looking for e parameter won't help. Each event has its own list of parameters passed to the callback; look it up in the documentation.
In case of the browserAction.onClicked:
The callback parameter should be a function that looks like this:
function(tabs.Tab tab) {...};
tabs.Tab tab
So the only information you get is the current tab at the time the button was clicked.