Popup positioned incorrectly (negative top) when `scrollableContainer` option is set — introduced in v5.2.0

[galloween]

Affected versions: 5.2.0+
Working versions: ≤ 5.1.0

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Description

When scrollableContainer is set to a custom element (e.g. a wrapper div with position: relative), popups such as the link-edit popup render with an incorrect top value — typically a negative number that places the popup above the container's top edge instead of near the selection.

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Root cause

In FroalaEditor.MODULES.position, the at(left, top, popup, height) function was changed in v5.2.0 to add a special case for position: relative containers:

// Step 1 — always runs:
t && (t -= c.offset().top)

// Step 2 — new in v5.2.0, runs when container is position:relative:
"relative" === c.css("position") && (
  o = (r = c.get(0)).getBoundingClientRect(),
  t = t && t - o.top + r.scrollTop
)

Both steps subtract the container's vertical position — offset().top (document-relative) and getBoundingClientRect().top (viewport-relative) — effectively double-subtracting and collapsing top to near zero.

v5.1.0 introduced the classList.contains("fr-toolbar") guard for the left offset (which is fine), but did not touch top.

v5.2.0 added the "relative" branch for top, which is the regression.

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Fix

The t -= c.offset().top in Step 1 should be skipped (or Step 2 should be the only adjustment) for position: relative containers. The v4.x / v5.0.0 / v5.1.0 logic — a single t -= c.offset().top — was correct.