Fitts' Corners

Edited the day after to be (hopefully) more clear and less mundane!

Procrastination led me to this article: Top 8 Reasons HCI is in its Stone-age.

Among other things he asks:

Why do modern Desktop Environments not exploit Fitts' Law?

One of the implications of Fitts' law is that there are five spots on a mouse-operated display that are easiest to target, the four screen-corners and the spot directly under the cursor. A default KDE setup with a maximised window has clickable widgets that respond to corner clicks. The K-Menu, the window-menu, the window-close button and the clock. Windows is the same. GNOME is debatably even better as all four corners always have something useful in them. But we could still make more use of the corners, they are after all extremely easy to hit. So why don't the desktops have behavior associated with simply moving the mouse into the screen corners?

In my opinion, it's because they are the easiest spots to hit with the mouse.

Setup your OSX box to trigger Expose when you move the mouse to a corner. Now count how many times during the day you nudge the mouse into the corner and trigger Expose by accident. It's very useful to be able to easily trigger Expose, but it's very annoying to be able to easily trigger Expose. The annoyance is such that I would definitely argue against inflicting such behavior on people by default. Apple apparently agree with me, by default you can only activate Expose with the F12 key.

Being Less Annoying

Launching a Konqueror instance, or KMail or doing something drastic like Expose would be annoying if done by accident. The new Windows would probably get in the way of what you were doing and Expose loses window focus and totally changes the screen contents. We want something that doesn't interfere with what the user was doing, but still is useful enough that we are making more use of the corners.

How about non-intrusive, inactive windows that appear from the screen corners? They could show a calendar, or the weather for this afternoon, or your CPU temperature. Well, maybe, but we can't show this passive-window in the same corner, or it would get in the way of the close button, or the K-Menu. So perhaps show the passive window in the horizontally opposite corner? Yeah I think that would perhaps be quite fun.

But this is hardly a revolutionary feature. The corners are the easiest spots to target on the desktop - you can hit them without looking at the screen! Yet, so far, my only suggestion that is both useful and not annoying belongs in the KToys module.

Better Uses For Hot-Corners

It seems to me we should trigger a really frequent task when the mouse hovers over a "hot-corner". For instance: "Copy text to clipboard". With some visual feedback, (perhaps Klipper shows a little non-intrusive popup that confirms the copy has occurred), this could be a nice feature.

But then again would the high rate of accidental activation just make it irritating? I get irritated already when I lose my middle-click clipboard contents because I accidently selected some other text. On the other hand I continue to use middle-click paste because it is so convenient despite its drawbacks. And even though the screen corners are mouse magnets, you don't often have text selected, so triggering the feature accidentally would be less common. If the Klipper notification had a button in it labeled "Revert to '((previous content))'", perhaps we would make accidental activation less annoying?

Perhaps I've got you thinking that I'm on to something. But generally when you want to copy some text, you've been typing, and having to move your hands from the keyboard to the mouse is bad ergonomics. But my idea would still work for copying a chunk of text from a web-page to the google-search-bar, etc. Perhaps the same corner could trigger paste if no text is selected.

Lets say we made the bottom right corner do this. We could even put the klipper applet in that corner to make the association more logical. But now imagine moving the mouse towards that corner with the intention of right clicking whatever applet is in the Kicker there. Can we imagine yourself getting more and more nervous as you realise you are getting closer and closer to the "hot-corner"? This is what makes me unhappy with the entire concept of just moving the mouse into a corner to trigger some function. I don't think it's a good idea to make users feel restricted about how they move the mouse!

But still I'd like to try out this copy/paste idea. Select text, hit corner, click paste location, hit corner. Quick and easy! Perhaps with practice I'd even learn not to accidentally trigger it. But I'm not convinced that hot-corners are a good feature for Desktops. I'm not surprised that hot-corners are not a default feature of most Desktop Environments.

Scrollbars

Changing topic slightly, there is one very important area KDE should take note of Fitts' law. Right hand edge scrollbars. OSX and Firefox do it properly - if the window is maximised or aligned with the right hand screen edge, you should be able to use the scrollbar with the mouse from the right hand screen edge. The problem for KDE is Qt. QScrollView puts the scrollbar inside a QFrame with a 3-4px margin, so there is always a slight margin between the screen edge and the QScrollBar widget. You can set the QScrollView to be frameless and remove the margin, and this is something I would like to see happen with most applications. The problem is that the frame is often an important visual separator. Certainly with amaroK I think our interface would look a lot more cluttered without the frame. Maybe we need a three-sided frame? Or just a divider top and bottom.

Times Expose accidently triggered while writing this post: 3
And twice more during subsequent edits!