I’ve used Mozilla Thunderbird to read my email for years, and for the most part, I think it’s a pretty nice email client. But lately I’ve developed an itch that really needed scratching.

I tend to use the keyboard to navigate around through applications, and so in Thunderbird, I find myself using TAB to switch between the list of mail folders on the left and the list of messages on the right.  The problem is that a few years back, when they added tabbed views, they changed the way that the TAB key works.  (I’ll try to be clear about the tabbed views and the TAB key, which unfortunately share the same name).  After the addition of tabbed views, the TAB key no longer toggled between just the (1) folders pane and (2) messages pane, but now it toggled between (1) folders pane (2) messages pane (3) tab selector widget.  So that means I had to re-train myself to press the TAB key once to go from folders to messages, and twice to go from messages back to folders.  But it got worse.  If you turn on something like the Quick Filter, the TAB key toggles between (1) folder pane (2) messages pane (3) tab selector widget (4) the Quick Filter.

Basically, the TAB key works like it does in a web browser, which is pretty much useless when there are so many widgets that can accept focus.

Today I discovered that what I was really looking for was the F6 key.  It strictly changes focus among the visible window panes.  For me, most of the time, that’s (1) folder pane (2) messages pane, but if I turn on message previews (rarely), it expands to (1) folder pane (2) messages pane (3) preview pane.

THIS MAKES SENSE.  Within the main window (tab) that I am looking at, the F6 key moves between the major window panes.  Awesome.

However, wouldn’t it be cool if I could use the TAB key to do this focus-switching, instead of lifting my fingers off of their pseudo-home position to get way up to F6 (which I can’t find just by feel — I have to look down at it)?

A little bit of searching led me to extensions, such as the very old but still usable “keyconfig”.  This is a pretty opaque tool that lets you insert some sort of arcane code into the prefs.js file.  Basically, it did not help me do anything, but it did help me understand how keys are mapped.  Deeper searches led me to the “DOM Inspector”, which lets you view the document that is being rendered (apparently, views in Thunderbird are pretty much HTML documents, which I suppose was hip at the time).  That led me to some of the arcane codes that are mapped to certain keys.

So here’s what I tried.  I looked at the arcane code that is mapped to F6, and I looked at the way “keyconfig” inserted some mappings of key names and their arcane codes. And I mimicked it.  I just added this line to prefs.js:

user_pref("keyconfig.main.xxx_key75_SwitchPaneFocus(event);", "][][VK_TAB][SwitchPaneFocus(event);][");

And wouldn’t you know… it worked! Now the TAB key does what the F6 key normally does… it switches focus among the main window panes in the active tabbed view. Yay, lazy fingers cheer!