Add a 1.5s idle-close timer to each header nav-tab dropdown. The timer
is armed when the menu opens and reset on any pointer hover or movement
over a menu row; on timeout the popup closes itself. Single-open is
already enforced by Slint, since only one PopupWindow can be open per
window, so sweeping across hover-to-open tabs closes the previous menu
automatically. Hover-to-open and click-to-open both remain working.
cc
vicrodh
b6355dc202