Scrollbar flashes when application is started

• I am on the latest Hyper.app version

• I have searched the issues of this repo and believe that this is not a duplicate

• OS version and name: macOS High Sierra

• Hyper.app version: Hyper 2.0.0-canary.14 (canary)

• Link of a Gist with the contents of your .hyper.js: Here's my config

• Relevant information from devtools (CMD+ALT+I on macOS, CTRL+SHIFT+I elsewhere): Nothing.

• The issue is reproducible in vanilla Hyper.app: This issue is reproducible with the vanilla Hyper.app if you set the backgroundColor to something like #555. Interestingly, it doesn't happen when the backgroundColor is set to #FFF.

Issue

As stated in the issue title already, the scrollbar flashes up when Hyper.app is started and also when a new tab is created. This is probably due to the backgroundColor that can be specified in the config file and only happens for certain colors. I am not sure why but if you for instance set it to #555, you'll see the scrollbar flashing up.

Same goes for panes. They flash up when I create new panes vertically as well as horizontally.

Here's a GIF showing the flashes:

Start by reproducing the flash in vanilla Hyper with the .hyper.js backgroundColor set to #555, then inspect startup, new-tab, and pane creation behavior with the devtools. Done means the scrollbar and panes no longer flash during those actions, including with background colors that currently trigger the issue.