Small windows and edge drawers
The window now goes down to 380 by 480 points. Columns that no longer fit beside the chat become drawers that slide in from the window edge.
Columns become drawers
As the window narrows, the chats sidebar goes first, then the session details, then the inspector. Each one becomes a drawer at its window edge instead of squeezing the chat. Rest the pointer on the edge and the drawer slides out. Click inside it and it stays. Click anywhere else, or press Escape, and it slides back.
Your own settings are never changed. A sidebar you had open docks again as soon as the window is wide enough. The title bar buttons and shortcuts open the drawer while the window is narrow.
Everything else fits too
Panes in a narrow chat column stack instead of sitting side by side. The place menu drops to one column. Tab rows scroll sideways instead of overflowing. Settings, Memory, Plugins, Doctor, Help, Gateway, Team and Versions all fit at 380 points with no sideways scrolling.