Enhanced options for various download commands about download_panel_tweaker

[Infocatcher]

Oh, too many things for options page...

Downloads menu item                               [Open old downloads window  v]
Downloads menu item in private window             [Default (don't override)   v]
“Show All Downloads” item                         [Default (don't override)   v]
“Show All Downloads” item in private window       [Default (don't override)   v]
Hotkey for downloads (Ctrl+J)                     [Toggle download panel      v]
Hotkey for downloads (Ctrl+J) in private window   [Toggle download panel      v]

[Infocatcher]

Oh, too many things for options page...

Current appearance:

A but tricky (for margins) and Firefox itself is buggy width menulists:

[Infocatcher]

Also we have "Downloads" button on about:home page...

chrome://browser/content/browser.js

messageManager.loadFrameScript("chrome://browser/content/content.js", true);

chrome://browser/content/content.js

  onClick: function(aEvent) {
    ...
      case "downloads":
        sendAsyncMessage("AboutHome:Downloads");

resource:///components/nsBrowserGlue.js => resource:///modules/AboutHome.jsm

  MESSAGES: [
    ...
    "AboutHome:Downloads",
    ...
  ],

  init: function() {
    let mm = Cc["@mozilla.org/globalmessagemanager;1"].getService(Ci.nsIMessageListenerManager);

    for (let msg of this.MESSAGES) {
      mm.addMessageListener(msg, this);
    }

Anyway, seems that we can't use this way to handle "AboutHome:Downloads" message (missing things like event.preventDefault()/stopPropagation()):
https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/nsIFrameMessageManager
https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/nsIFrameMessageListener
But we still can handle "click" event before content script...