Kanban: drop-target highlight sticks on columns after drop #113

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opened 2026-04-22 07:19:07 +00:00 by zaelgohary · 0 comments

zaelgohary commented

2026-04-22 07:19:07 +00:00

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Two root causes:

Per-column is_drag_over: Signal<bool> cannot be cleared reliably — HTML5 ondragleave fires when the cursor crosses child nodes inside the same column, so the signal flips false-true-false rapidly and often ends up stuck true.
The active-branch border/background strings are literals (2px dashed #007AFF) while the inactive branch uses var(--color-border, …). Dioxus 0.7's inline-style diff drops updates when a style attribute transitions between a literal and a value containing var(...), so the DOM keeps the last literal forever.

Dragging a task across columns leaves every traversed column with the blue dashed drop-target border burnt in. The highlight is never cleared — even after dropping on a column or leaving the board, every column the cursor passed over stays highlighted until the next full re-render. Two root causes: 1. Per-column `is_drag_over: Signal<bool>` cannot be cleared reliably — HTML5 `ondragleave` fires when the cursor crosses child nodes inside the same column, so the signal flips false-true-false rapidly and often ends up stuck true. 2. The active-branch border/background strings are literals (`2px dashed #007AFF`) while the inactive branch uses `var(--color-border, …)`. Dioxus 0.7's inline-style diff drops updates when a style attribute transitions between a literal and a value containing `var(...)`, so the DOM keeps the last literal forever.