[Bug] Buttons briefly wrong size during transition

[laurensvalk]

Describe the bug
When the install (or run) buttons change state, there's sometimes a brief glitch. It's not always too noticable, but sometimes it is.

It looks like this:

Version 91.0.4472.101 (Official Build) Built on Ubuntu , running on Ubuntu 18.04 (64-bit)
Pybricks Code v1.0.0

Expected behavior
The buttons do not change size.

[laurensvalk]