From a322516f33d18ff9203078aed13d890f31ed1437 Mon Sep 17 00:00:00 2001 From: Lionel DARNIS Date: Wed, 22 Apr 2026 11:09:46 +0200 Subject: [PATCH] segmented_button: fix internal tab reorder end-to-end MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Two independent bugs prevented tab drag-and-drop reorder from working on cosmic-comp (and likely other compositors): 1. allow_reorder required DndAction::Move to be negotiated via OfferEvent::SelectedAction, which cosmic-comp does not always emit for self-drops (the SelectedAction event either never arrives or arrives with DndAction::empty()). Add a fallback: accept self-drops whenever state.dragging_tab is set. dragging_tab is only populated by start_tab_drag on this same widget, so this is safe; mime match and on_reorder presence are checked below. 2. reorder_event_for_drop preferred drop_hint.side over positional swap, producing counter-intuitive no-ops: dropping A (pos 0) on the left half of B (pos 1) resolved to "Before B" which, after removing A, lands at pos 0 again — the tab appeared not to move. Always use default_insert_position, which derives direction from dragged vs target positions (Konsole/Firefox/Chrome-style swap semantics). Co-Authored-By: Claude Opus 4.7 (1M context) --- src/widget/segmented_button/widget.rs | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/src/widget/segmented_button/widget.rs b/src/widget/segmented_button/widget.rs index 7195c9d8..9ddd7d8d 100644 --- a/src/widget/segmented_button/widget.rs +++ b/src/widget/segmented_button/widget.rs @@ -406,11 +406,12 @@ where { return None; } - let position = state - .drop_hint - .filter(|hint| hint.entity == target) - .map(|hint| InsertPosition::from(hint.side)) - .unwrap_or_else(|| self.default_insert_position(dragged, target)); + // Always use positional swap (Konsole/Firefox/Chrome semantics): + // dropping onto any part of a different tab swaps it with the dragged + // tab. drop_hint.side-based Before/After is counter-intuitive: dropping + // A (pos 0) on the left half of B (pos 1) resolves to "Before B" which, + // after removing A, lands at pos 0 — so the tab appears not to move. + let position = self.default_insert_position(dragged, target); Some(ReorderEvent { dragged, target, @@ -1201,7 +1202,14 @@ where .dnd_state .drag_offer .as_ref() - .is_some_and(|offer| offer.selected_action.contains(DndAction::Move)); + .is_some_and(|offer| offer.selected_action.contains(DndAction::Move)) + // Self-drop fallback: some compositors (cosmic-comp + // observed) do not emit OfferEvent::SelectedAction for + // internal drags, leaving selected_action empty. + // dragging_tab is only set by start_tab_drag on this + // same widget, so this covers the self-drop case + // safely; mime and on_reorder are checked below. + || state.dragging_tab.is_some(); let pending_reorder = if allow_reorder && self.on_reorder.is_some() && self.tab_drag.as_ref().is_some_and(|d| d.mime == *mime_type)