Add keyboard shortcut ('t') to show the tag list dropdown for the active [floating] entry.

feedly-tag-dropdown-shortcut.user.js

// ==UserScript==
// @name         Feedly Open Tags Dropdown
// @namespace    http://prw.prehiti.net/
// @version      0.9.14
// @description  Show the Feedly tag entry dropdown with a keyboard shortcut.  This functionality should be builtin!
// @author       Payton R White
// @include      http://feedly.com/*
// @include      https://feedly.com/*
// @include      http://*.feedly.com/*
// @include      https://*.feedly.com/*
// @grant        none
// @require      http://code.jquery.com/jquery-1.12.4.min.js
// ==/UserScript==

jQuery.noConflict();

console.log("loaded feedly open tags dropdown user script");

// https://stackoverflow.com/a/21696585/5305104
function isHidden(el) {
    var style = window.getComputedStyle(el);
    return (style.display === 'none');
}

function doSetup() {
    console.log("OpenTagDropdown doSetup called");

    var dropdown_key = 0x54;  // "t"

    jQuery(document).keydown(function(e) {
        if ( e.which == dropdown_key && !(e.altKey || e.ctrlKey || e.metaKey) ) {
            console.log("OpenTagDropdown got tag dropdown_key");
            var ret = jQuery("#floatingEntry .icon-fx-star-save-ios-md-black:last");    // wish there was a less cheesy selector for the button
            var focus = document.activeElement;
            var inputFocus = focus instanceof HTMLInputElement;
            if(ret.length === 1 && !inputFocus) {
                button = ret[ 0 ];
                console.log("OpenTagDropdown found the tag button!!!");
                console.log("OpenTagDropdown button is: " + button);
                button.click();
                console.log("OpenTagDropdown synthesized a click in tag list button!");
                e.preventDefault();
            } else {
                console.log("OpenTagDropdown tag dropdown couldn't find 1 dropdown button with selector");
            }
        }
    });
}

jQuery(document).ready(function () {
    doSetup();
});