This is my idea. All is built on one XUL file.
Basic options.
I added one new button for open advanced/basic window. After click this button we will be see advanced options window.
After click on Basic Options button we will be see basic options window.
If you accept this idea we can work for fully working.
What we obtain?
1. Only one window for all options and accounts settings
2. Many entities for basic options window will be redundant (about 60) - we can remove them from .dtd file
3. Description in the basic options window going to window size. Long translation will be wrapped. (this sentence will be in the one entity, now is in the two entity)
4. We can remove 'basic-options.xul' file (about 25 kB less)
5. Clear code