Terminal not detecting full-screen mode correctly

[gtritchie]

1.1.383, any platform, desktop or server

• Start a terminal in RStudio
• Run a full-screen program such as vim or tmux
• Tools -> Terminal -> Terminal Diagnostics

Expect
Full screen: 'client=true/server=false'

Actual
Full screen: 'client=false/server=false'

This is a regression from taking xterm.js 2.9.2: #1444 late in the 1.1 release. Problem not in xterm.js, but in a change in how RStudio code needed to detect alt-buffer. Easy one-line fix, coming shortly.

This has a several visible consequences, one of them is breaking #1437:

• Run tmux, open multiple panes within it
• Ctrl+L

Expect: terminal should recognize it is running a full-screen program, and pass the Ctrl+L to that program, so instead of clearing the entire terminal should clear just the active pane.

Actual: ctrl+L is treated as clear-entire-terminal, messing up tmux display

Another is that when running a full screen program, the Stop Sign and Clear icons are supposed to be hidden on the terminal toolbar, but they are still being shown.

[jmcphers]

Backported to 1.1 here: 59306a4

[ronblum]

Confirmed using vi, tmux, and hangman.