Hide the window after a period of inactivity about key-mon HOT 5 CLOSED

Yep, that is exactly what I meant :)
The reason is as follows. I like the large-scale images, because they are very 
clear to the watcher. However, when working with a full-screen application, 
these might be in the way of something you would like to show in your tutorial.

Issue 72 has been merged into this issue.

I thought this is related to Issue 72, but it's not after another read.

Unmerging Issue 72 and changing the issue summary.

Fix typo. (Wish we have minute-edit feature on Google Code)

In re5386f8973d6. (stepped on another commit-log command mine, have to close 
manually)

Anyway, please test it.

On my computer, it doesn't seem to be happy with xcompmgr + opacity setting. 
Some strange artifacts around transparent area. I thought it might be wrong 
about how I generated mask, but then I found two examples, though both are not 
generating mask as I did in key-mon code. They just use mask from image/XPM. 
After I use transset-df to set the opacity on them, they also have similar 
issues.

I believe that's something wrong with my X composition stuff. (Never got to 
understand it)

So, I think it should be fine to push the code.