Great, it works!
Sorry, I didn't try to collapse the panes in the library tab.
Thanks

It’s the panes in the library tab, not the reader.

@dhbpac: Again, it's the panes in the library tab that matter here, not the tabs in the reader.

We're not talking about standalone reader windows. We're talking about the main window, which has a library tab and any number of reader tabs.

You need to switch to the first tab — which shows your library — and narrow or close the left and/or right panes, showing collections and item data. You can then narrow the window much more, including in reader tabs.

In an upcoming version, we're going to have Zotero automatically switch into a mode for narrower-width windows when the window is narrowed, but for now, the window's minimum width depends on the panes in the library tab.

In the latest beta version, Zotero will automatically shrink the left and right library panes as you narrow the window and, ultimately, switch automatically into Stacked layout mode, where the item pane appears below the items list. This allows the window to be made very narrow. If you then increase the width again, it will automatically switch back to Standard layout mode.

(At very narrow widths, the reader toolbar buttons will start to overlap, but we'll fix that.)

The automatic switch to stacked mode is neat, but there seems to be an issue whereby Zotero will not resize itself smaller than a certain size, even if there's enough room and doing so means adding a bunch of blank space. This conflicts with the expected behaviour of the Windows window snapping feature, hindering multitasking with other programs. See attached screenshots:-

My current layout fullscreen:

https://s3.amazonaws.com/zotero.org/images/forums/u1359206/fnigw3fr8sc0y7rq6qsg.png

My layout if I snap the window to the left edge of the screen (which I would expect to make the window half the screen width, as it does with almost every other Windows program):

https://s3.amazonaws.com/zotero.org/images/forums/u1359206/mphpnsqb1ufp7qq12kkl.png

Is this a bug or intended behaviour? If intended behaviour, is there a setting to change or override it? Manually setting the column sizes in the item pane either when maximized or when snapped does not affect the behaviour.

EDIT: to clarify, I would like Zotero to respect the normal Windows snapping behaviour (or the option to make it do so), i.e. in most cases snapping the window to the edge of the screen by dragging or Win+Left/Right should make the window half the screen width.

If it helps diagnose the issue, this seems to be specific to snapping a window that's in Standard Layout to a size that would cause it to change to Stacked Layout. Snapping a window that's already in Stacked Layout behaves as expected. Using the new Windows 11 snapping options from the pop up ribbon at the top of the screen when dragging behaves as expected.