Selection becomes non-transparent on app switch

Version information

Thunar 4.20.1. Calculate Linux (Gentoo-based).

Steps to reproduce

1. Open Thunar.
2. Start a files selection by click-and-drag.
3. It is semi-transparent.
4. Switch to another app clicking <Alt>-<Tab>.
5. The selection becomes non-transparent.

Current behavior

The selection becomes non-transparent.

Expected outcome

The selection is still semi-transparent.