Tray: unread messages icon fix for linux

[Aitchessbee]

Fixes #1364

You have tested this PR on:

• Windows
• Linux/Ubuntu
• macOS

[Aitchessbee]

So the issue was in the window.devicePixelRatio used in renderCanvas code (that is only being run for linux). window.devicePixelRatio takes the value of the scaling factor set on your linux PC, and if it's anything other than 1, the icon breaks... With the scaling factor set to 1 the icon stays the same size irrespective of the scaling factor, which also matches the other tray icons that I had (cloudinary and slack)...

Old -

New -

[alya]

Thanks for the fix! Could you please update your commit message to match the commit style guidelines?

Also, please add before/after screenshots to the PR description.

[Aitchessbee]

Done! Let me know if there are any other changes...

[mkaminsky]

I've had this problem for a while, under both X11 and Wayland, using a 4K screen with my display scaled to 200%.

I wanted to confirm that the fix here works for me--thanks @Aitchessbee

Would love to see this PR included in the next release. Thanks for all the great work on Zulip!

[alya]

@andersk are you up for reviewing this proposed one-line change?