Backgroundcolor of resettable selectinput in focus does not cover complete input

[lvernaillen]

What you were expecting:
When a resettable SelectInput gets focus, a darker grey background is applied which covers the complete input.

What happened instead:
Only part of the input gets the darker grey background leaving the right part (padding) of the input next to the dropdown glyph in light grey color.

Steps to reproduce:

• Open the simple blog demo
• Go to the Posts list view
• Select a post to go to the post edit view
• Select the Miscellaneous tab
• Notice Category selectinput has light grey background
• Select a different value for the Category selectinput
• Notice only part of the focussed Category selectinput has dark grey background

Related code:
https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple

Other information:
SelectInput without the resettable prop does not show this behavior.

Environment

• React-admin version: tested on 4.1.0 and master
• Last version that did not exhibit the issue (if applicable): ?
• React version: 17
• Browser: Version 103.0.5060.114 (Official Build) (64-bit)

[fzaninotto]

Reproduced, thanks!