Firefox Mini Window moves a whole tab or a selected part of a webpage into a compact window that stays above other windows. Mozilla lists it in Firefox Nightly 161.0a1; the steps below use Mozilla’s documented menus for moving and returning content. Mozilla’s Nightly release notes describe the feature.

What Firefox Mini Window does

Use Mini Window to keep a webpage or a specific section visible while you work in another window. It moves the tab or section: the content is no longer accessible in the regular Firefox window until you return it. Mozilla explains the move behavior and controls.

Move a whole tab

A Firefox tab context menu is open, with “Move to Mini Window” highlighted in a submenu and marked “Beta.”
  1. Right-click the tab you want to move. This opens its context menu.
  2. Choose Move Tab > Move to Mini Window. Firefox opens that tab in the floating window.

Move a selected page section

BrenTech’s Firefox Nightly demonstration shows both ways to move content, resizing the window, and returning it to Firefox.
  1. Right-click the webpage content containing the area you want to keep visible.
  2. Choose Move Section to Mini Window.
  3. Select the part of the page to move into the window.

This option is useful when you need one section of a page rather than the full tab. Mozilla also documents an optional shortcut: right-click the toolbar, choose Customize toolbar, then drag the Mini Window icon onto the toolbar.

Return the content and check the move

A desktop document window with a smaller browser window displaying a webpage over its right side.

A Mini Window stays on top of other windows. To confirm the move, check that the chosen tab or section is in the floating window and no longer accessible in the regular browser window. Use the return control in Mini Window to send the content back. Mozilla also lists closing the window and muting or unmuting it when audio is playing as available controls.

Mozilla’s release plan and website access

Mozilla planned to bring Mini Window to the release channel with Firefox 160 on November 10. A Mozilla employee also said the planned availability would be simultaneous across platforms. Mozilla’s Nightly release notes caution that features listed in Nightly may not make a final Firefox release.

Mini Window is a user-triggered browser feature: a Mozilla employee said websites are not given an API to open it. The same reply pointed to the separate Document Picture-in-Picture standard as similar in purpose.