Spinners in console applications make selection difficult

[Tyriar]

From what I can see, spinners like in npm or https://github.com/sindresorhus/elegant-spinner cause the entire viewport to be destroyed and re-rendered. I believe this is why selecting text is difficult when a spinner is active. If the entire viewport is indeed being re-created this certainly wouldn't be good for laptopbattery either.

Details

• Browser and browser version: VS Code/electron
• OS version: Ubuntu 16.04
• xterm.js version: 8a124d0

Steps to reproduce

1. Clone vscode
2. Run ./scripts/npm.sh install --arch=x64
3. Try selecting text in the terminal

[parisk]

I think the issue might be here: https://github.com/sourcelair/xterm.js/blob/master/src/xterm.js#L1075.

If this is a "big refresh", then xterm.js removes all rows from the DOM for faster calculations and this messes up with selections.

I am not sure what could be the best solution here. Three things come in mind:

1. Smartly update the DOM contents of the terminal in order to avoid messing up with selection
2. Restoring selection programmatically after a refresh (which might feel patchy for the user)
3. Implement virtual selection Implement virtual selection #207

While 3. needs the most effort to get right, I guess that it is the best and most future-proof solution.

[Tyriar]

Well if we can shift the elements upwards without removing the elements from .xterm-rows (1.) and the selection is retained then this would be an ideal step before 3.

[akalipetis]

We could also use HTML fragments and partially updating them. This would be a nice idea too IMO.

After a quick Google search I found this one: https://github.com/fiduswriter/diffDOM

[Tyriar]

Duplicate #468

[Tyriar]

Fixed in #670