userChromeJS

Tested on Firefox Developer Edition 70.0b14, Windows 10

Instructions

1. Save config.js to Firefox installation folder (usually C:\Program Files (x86)\Mozilla Firefox), next to firefox.exe.

2. Save config-prefs.js into \defaults\pref inside Firefox installation folder (usually C:\Program Files (x86)\Mozilla Firefox\defaults\pref), next to channel-prefs.js.

3. Click Firefox menu button (☰) -> Help -> Troubleshooting information (or simply open the address "about:support"), then click Open folder. This is the folder of your Firefox profile. In there, create a new folder called chrome.

4. Inside chrome, create another new folder called utils, then save all these files into it.

5. Save the desired userChromeJS scripts into chrome. Read below the description of some of them.

6. If you want a button to manage your userChromeJS scripts, save rebuild_userChrome.uc.js into chrome.

7. Restart Firefox.

userChromeJS scripts

(click to expand)

Enter Selects

Preselects the first suggestion from address bar. For instance, if this page is the first suggestion when you type "xiaoxiaoflood", you don't need to press down arrow key before Enter. This is a workaround for the bad Firefox design choice of autofill domains only.

This script replaces autofill, so browser.urlbar.autoFill is disabled on install. If you are typing part of a domain from the start and the first suggestion is from that domain (for instance, git from github.com), Tab key will autocomplete the domain even if the first suggestion is not the root.

I suggest to set browser.urlbar.suggest.searches = false or browser.urlbar.matchBuckets = general:5 (general:5 means 5 normal suggestions before search suggestions, adjust the value as you wish).

Download link.

Extension Options Menu

A single toolbar button to manage all your extensions. It opens a menu listing each extension. Left-click to open Options from the hovered addon, right-click to enable/disable, Ctrl + right-click to uninstall. Hover anywhere on the menu to see more.

Screenshot:

Download link.

Master Password+

Locks Firefox with password. This will prompt the password on browser startup or anytime when you lock it with Ctrl+Alt+Shift+W.

You need to set a master password in Firefox Options > Privacy & Security > [×] Use a master password.

Download link.

Locked:

Unlocked:

speedupcanonizeURL

Strings like "extensions.legacy.enabled" should load results in your default search engine when you press Enter in addressbar. Instead, Firefox tries to load the website "extensions.legacy.enabled", which of course doesn't exists. This script solves it.

Download link.

Status Bar

Brings back the good old status bar (also known as Addon Bar) at the bottom, with status text plus any buttons you want.

Screenshots:

Download link.

StyloaiX

Basic UserStyle manager with the same power of userChrome.css and userContent.css (can restyle both Firefox windows and websites). It loads .css files from \chrome\UserStyles. It supports instant enable/disable per style or global. It also can reload updated styles and load new ones. More features may be added in the future. To reskin websites, Stylus is a better option, with more features including autoupdate for styles available on the web. But Stylus can't touch the Firefox interface, only websites.

Note: just like Stylish, UserStyles are loaded by default as AUTHOR_SHEET. If you need AGENT_SHEET or USER_SHEET (for instance, userContent.css is USER_SHEET), save the file as ".as.css" or ".us.css".

Screenshot (yes, I'm using the old Stylish icon):

Download link.

Screenshots

userChromeJS Manager (the blue ones are restartless)

Status Bar, Extension Options Menu, MinMaxClose Button, newDownloadPlus.uc.js and legacy extensions: