Moving tabs across windows copies them instead

[sig-kill]

Steps to reproduce

• Open Firefox in a new profile
• Install Sidebery
• Open a new window (shown left)
  • 
• Drag a tab from one Sidebery panel to the other

Actual behavior

Tab is copied over to the new window, and not active:

Expected behavior

Tab should be moved from the old window and made active in the new window. Result in the example should be this:

Moving tabs used to behave this way seamlessly (even moving a playing Youtube tab across windows worked without interrupting the video) so it seems like there's a regression.

System

Windows 10

Firefox version

129.0b5

Sidebery version

5.2.0

Logs

No console logs