Xterm.js: Terminal background initially has wrong size

[takluyver]

We've started seeing this since we upgraded xterm from 2.2.3 to 2.3.1 in Jupyter:

We're passing in rows and cols options when we instantiate Terminal, and I've checked that rows is being passed a sensible value, but the background (xterm-viewport div) is not getting the correct height. As soon as resizing the window triggers the terminal to resize, it corrects itself and displays correctly.

Apologies if we're doing something stupid here, but we're currently stumped as to what it could be.

Details

• Browser and browser version: Reproduced on Firefox 51 and Chromium.
• OS version: Ubuntu 16.04
• xterm.js version: 2.3.1

Cross-linking jupyter/notebook#2172

[Tyriar]

I can repro this if I disable calls to resize in the demo, it's caused by optimizations to the system that measures character width/height size (CharMeasure).

[takluyver]

Thanks, upgrading to 2.3.2 does indeed solve the issue we saw.