Theia: Warn before closing a terminal

[sh7dm]

Description

Show a warning if user attempts to close a terminal which has running processes in it.

Reproduction Steps

1. Run a command (e.g. top) in Theia terminal and any other one.
2. Close both terminals

OS and Theia version:
OS: Ubuntu 19.10
Theia: master

Diagnostics:

[akosyakov]

I am not sure whether it is possible. Terminals are stream based, we don't really know what a user is doing. We could have something like that for tasks.

cc @elaihau @RomanNikitenko @marechal-p ?

[marechal-p]

I think a new internal method was added to test if a shell has a subprocesses running (meaning the shell is in use). See https://github.com/eclipse-theia/theia/blob/master/packages/terminal/src/node/shell-terminal-server.ts#L66-L88

[elaihau]

I think a new internal method was added to test if a shell has a subprocess running (meaning the shell is in use). See https://github.com/eclipse-theia/theia/blob/master/packages/terminal/src/node/shell-terminal-server.ts#L66-L88

+1

[akosyakov]

We should check though it does not break VS Code extensions. If they can close terminal programmatically then there should not be such dialogs. Maybe also make it configurable via preferences.

[sh7dm]

@akosyakov right, it should work only when clicking X button manually, not by commands. Preference should be added as well, but its default must prevent closing.