"Select all" is not synced to drive selection state

[jacobgkau]

Distribution (run cat /etc/os-release): Pop!_OS 21.10

Related Application and/or Package Version (run apt policy $PACKAGE NAME): eb02826 (master), b02ebf5 (master - 1), e9512a7 (gtk-rs-0.15).

Issue/Bug Description: If I select all the drives in the list, the "Select all" checkbox does not become checked. This means I can check it manually, which does nothing.

Similarly, if I check the "Select all" checkbox, then deselect one or more drives from the list, the "Select all" checkbox does not become un-checked, which means I need to un-check it manually before I can use it again.

Steps to reproduce (if you know): Open Popsicle with one drive connected, check the box next to the one drive.

Expected behavior: The "Select all" checkbox should become selected if all of the drives are selected, and vice versa.

Other Notes: