Firefox Nightly Tests Mini Window for Persistent Tab Overlay

Firefox Nightly has gained an experimental feature called Mini Window. The feature turns a browser tab into a separate window that stays above the current tab. In this mode, Firefox hides the usual browser chrome, including the address bar, navigation controls, and scrollbar. The page content then becomes the main visible surface.

How Mini Window Works

Mini Window is built around a persistent overlay within the browser window. Once a tab is put into Mini Window mode, its content remains visible above whichever tab the user is actively using. The address bar, controls, and scrollbar are hidden by default. When the mouse moves over the Mini Window, those elements reappear. Moving the cursor outside the window hides them again.

The intent is to support reference-style workflows. A user can write in one tab while keeping another page visible for consultation. This removes the need to switch back and forth between two tabs repeatedly. Because the hidden chrome frees up visual space, the Mini Window can stay compact without showing navigation elements that are not needed during passive viewing.

Compared with Picture-in-Picture

Mozilla describes Mini Window as similar to video picture-in-picture. Standard picture-in-picture works by extracting a video element from a page and playing it in a floating overlay. Mini Window takes a different approach: the entire tab remains intact. Text, images, form fields, and embedded media all appear in the overlay. Only the browser’s own interface is removed.

That difference extends the pattern beyond video. Static references, documentation pages, chat windows, and live dashboards can all stay visible while the user works elsewhere in the browser. The trade-off appears when the user needs to interact with the Mini Window. Since scrollbars and controls are not shown until hover, scrolling or navigating within the overlay takes an extra step. This may be acceptable for reading-oriented tasks but could feel slow during active use.

Limited to Nightly

The feature is currently available only in Firefox Nightly, Mozilla’s nightly build channel used for early and unstable feature testing. It has not appeared in Beta or release versions. Nightly changes are subject to revision or removal, so the final behavior may differ from this initial implementation. Mozilla has not yet shared details about how users enable the mode, whether the Mini Window can be resized, or how it behaves across different desktop environments.

Mini Window targets a recognizable pain point: keeping reference material visible without abandoning the current tab. Existing solutions often involve splitting the browser window, using multiple monitors, or relying on video-specific picture-in-picture. A tab-level overlay could reduce context switching for certain workflows. However, the interaction model still has to prove whether hidden controls create more friction than they save. For now, it is a focused experiment worth watching.

Window Placement and Interaction Questions

Because Mini Window remains above the current tab, its placement and size will shape how useful it feels. The available information does not say whether users can move the window, resize it, or keep it in a fixed position while switching tabs. It also does not specify whether the window stays above the current tab only, or above other application windows as well. These factors matter for tasks that require constant visual attention. A reference panel that moves unpredictably or gets lost behind other windows would undermine the feature’s main benefit.

This kind of unresolved behavior is normal for a Nightly feature. Mozilla frequently tests interaction ideas in a rough form before deciding how they fit into the browser’s larger UI. The Mini Window experiment may evolve rapidly, or it may remain an optional tool for a narrow set of users. The current state is an early look at a possible alternative to tab switching, not a finished product.