App Icon is missing in some places in GNOME

[ziggy42]

Description

The app icon is missing in some places:

I'm using the Appimage. I think that's the problem, because I have the exact same problem with NoSQLBooster and they're using Appimages too.

Version

GitHub Desktop version: 1.0.11
OS version: Fedora 27 with GNOME

Steps to Reproduce

1. Launch the app
2. Observe the icon is missing

Expected behavior: The icon is present

Actual behavior: The icon is not present

Reproduces how often: 100%

[picandocodigo]

This happens when running the app from source in development mode too. It could be some configuration that's missing in electron specific to Linux.

[shiftkey]

The fact this occurs in development mode as well as after installation probably means it's something related to the configuration values passed to electron-packager. And I did find this important note in the docs:

Linux: this option is not required, as the dock/window list icon is set via the icon option in the BrowserWindow constructor. Please note that you need to use a PNG, and not the OS X or Windows icon formats, in order for it to show up in the dock/window list. Setting the icon in the file manager is not currently supported.

Long story short, we should be able to fix this by setting icon as part of constructing the BrowserWindow instance here: https://github.com/desktop/desktop/blob/master/app/src/main-process/app-window.ts#L36-L62

We should only do this for Linux, which we can check at runtime using the __LINUX__ global.

[Croydon]

I can confirm the same issue for Fedora 26 with KDE.