Reopening — investigation in May 25 2026 session shows this is the visible symptom of a broader Windows-level activation regression affecting docked sub-forms, not isolated to popup paint.

After switching tabs (inside DiagramDesigner or between docked forms), several activation-dependent features break until any left-click anywhere restores them:

• Diagram right-click popup menu paints empty / needs mouseover to render items
• Listview hottracking in other docked forms (e.g. ProjectFrm) stops responding to hover
• Right-click on the diagram requires a prior left-click on the surface to route correctly

Released installers compared on this machine:

• 14.0.0.56644 (Jan 21 2025) — works
• 14.2.3.56987 (Jul 19 2025) — works
• 14.3.2.57055 (Oct 2 2025) — works
• 14.4.0.57301 (Feb 27 2026) — broken
• 15.0.0.57359 (Apr 10 2026) — broken
• current builds — broken

Workaround: left-click anywhere on the docked-form surface after a tab switch; popup and hottracking behave normally afterwards.

Partial mitigation: the cursor / hot-track collateral symptoms on the legacy TDrawing surface have been resolved by 0005620 (cursor feedback now consistent on labels/concepts/containers, and hot-track highlight paints without requiring the drawing to hold keyboard focus first).

The remaining symptom is the initial popup-menu paint on the new techserv/Diagram surface (NewTest tab) — right-click shows the menu frame but items only render after a mouseover. The legacy TDrawing popup no longer exhibits this after 0005620. The underlying activation regression (note 0006208) is unchanged.