STR : Apply the following script using scratchpad to any page document.addEventListener("keydown", function(e) {console.log("down " + e.keyCode);}, true); document.addEventListener("keypress", function(e) {console.log("press " + e.charCode);}, true); document.addEventListener("keyup", function(e) {console.log("up " + e.keyCode);}, true); then do the following key sequence 1. Alt down 2. R down 3. R up 4. Alt up (any other key can be used in step 2 and 3) the last Alt up does not trigger a keyup event and the console logs can be used to verify that

On Linux there is alt-up, but I don't see it on Windows.