It is surprisingly poor written to me. This are some of the thing that has to be changed:

  1. input tag is self closing - options.html
  2. When using jQuery you should not use document.getElementById, innerHTML - notification.html
  3. function pausecomp(millis) seems like "busy waiting" - background.html
  4. html tags interpreted ( wow )

Edit:

 1. It is more of a must than can, actually [w3][1]. Inputs must be self closing unlike in the file options.html, where all of them are like:
    
    `<input>...</input>`
 2. When jQuery is used there is no reason to continue with the usage of:
    1. `document.getElementById` - jQuery provides selector - **$('#...')**
    2. `innerHTML` -  - jQuery provides method - **$().html()** 
 3.  agreed.
 4. If a question from Stackoverflow, for example like [this][2], contains html tag with **<>**, the tag is interpreted. So you will receive this question with an actual input. Maybe I should write something there, like sanitize.

Something new to fix:

 1. Using both `new Array` and `[]` is sign of bad style. You should chose one, and as SO community strongly suggest it should be `[]`

  [1]: http://www.w3.org/TR/html4/interact/forms.html#h-17.4
  [2]: http://stackoverflow.com/questions/5934300/c-inserting-input-in-htmldocument