Blessed xterm fixes

[johnpoth]

In this PR I propose to

1. remove the cloning of the options as it may result in errors when using the parent:screen option.
2. make blessed-xterm work in the browser as the global.window is read only.

Thanks!

[rse]

In my code comment for the clone() usage, I wrote: "clone options or all widget instances will show at least the same style, etc" How do you think this issue is now adresses by just removing the clone() call? I do not see what you are doing instead?

[johnpoth]

Hi @rse , thanks for reviewing! I saw the comment. Could you please elaborate the problem of widgets having the same style? I tried reproducing using the sample.js file by applying different styles to the two terminals and it worked without the clone() call. Thanks!

[rse]

I've currently no time to reproduce, but AFAIK the issue was that the style of a window being rendered active, or scrolling (in visual mode) or in error state was broken without this. One of those three states was not rendered correctly AFAIK.

[johnpoth]

@rse no worries I'll try to reproduce on my side too.

From a design standpoint I don't think it should be needed to clone the options. So if it is needed I think it would be more of a bug in blessed/blessed-xterm. My 2 cents ofc :)