Fix (InitialBalance): lifecycle, validation and code-health cleanups

[AlbertoAmadorBelchistim]

InitialBalance: lifecycle, validation and code-health cleanups

This PR bundles a set of small, self-contained fixes and clean-ups for InitialBalance.cs. Each commit is independent and easy to cherry-pick or revert; happy to split into separate PRs if preferred.

Changes

1. Release PropertyChanged subscriptions in OnDispose — the constructor wires nine ValueDataSeries.PropertyChanged handlers and never detaches them, so they accumulate as zombie subscriptions across reloads. Adds the missing OnDispose that mirrors every += with a matching -=.

2. Subscribe _mid to PropertyChanged so its labels react to color changes — _mid is the only series with a dedicated branch in GetLabelTagSuffixes that was not subscribed in the constructor. As a result, changing the Mid color in the property grid did not refresh the "Mid" AddText labels. Adds the missing subscription for parity with the other nine series.

3. Disambiguate StartTime / EndTime display order — both properties were declared with Order = 20 inside the SessionTime group, leaving their relative order in the property grid undefined. Bumps EndTime to Order = 25.

4. Constrain X1 / X2 / X3 multipliers to a positive range — adds [Range(0.1, 100)] to the three multipliers. Negative values used to invert the extension levels (IBHX* below the IB high, IBLX* above the IB low).

5. Remove the unused using Pen = CrossPen; alias — the alias is never referenced; every site uses CrossPen directly.

6. Mark RangeDataSeries fields as readonly — the eight fields are initialized at declaration and never reassigned. Matches the convention already used by the ten ValueDataSeries in the same file.

7. Skip the _endTime assignment when PeriodMode is Bars — in Bars mode the session-end check is bar - _lastStartBar >= Period and _endTime is never read. Wraps the assignment in if (PeriodMode is PeriodType.Minutes) so the dependency between _endTime and PeriodMode is explicit.

End-user impact

• Memory: lower across reloads (fix 1).
• UI correctness: Mid label color now updates with its series (fix 2); SessionTime properties have a deterministic order (fix 3); multipliers cannot produce crossed bands (fix 4).
• Visual output: unchanged on existing charts.

Open questions for the maintainers

A few decisions I would rather defer to you than take unilaterally:

1. What is the intended state of the _mid series?

_mid is initialized with CrossColor.FromArgb(0, 0, 255, 0) — A = 0, fully transparent — so the line and its "Mid" AddText labels are invisible by default. At the same time, the series is still calculated every bar, exposed in the property grid (color editable), described via SessionAveragePriceDescription and labelled in the OnCalculate text block. Two equally plausible interpretations:

• Bug. The intended default was visible (e.g. FromArgb(255, 0, 255, 0)). Follow-up: pick a sensible default such as DefaultColors.Green.Convert().
• Soft-deprecation. The series is being phased out but kept around so chart templates that reference "MidId" still load. Follow-up: replace the alpha=0 trick with the canonical hidden-series pattern (VisualType = VisualMode.Hide, IsHidden = true) and drop the now-dead "Mid" AddText call together with the _mid branch in GetLabelTagSuffixes.

Could you confirm which one is intended? I held this fix out of the present PR on purpose and am happy to send the matching patch as a small follow-up.

2. Renaming the unprefixed value fields

The internal value variables ibhx1..3, iblx1..3, mid (lines 199–206) are the only fields in the file without the _ prefix that the rest of the private state uses. Renaming them to e.g. _ibhx1Value..3, _iblx1Value..3, _midValue would make the distinction between the value (ibhx1) and the corresponding ValueDataSeries (_ibhx1) explicit and remove an easy-to-confuse shadow.

The change would touch every call site inside OnCalculate and the labels block — a noisy diff for a cosmetic gain — so I left it out of this PR. Would you take it as a separate chore: rename internal value fields in InitialBalance PR, or would you rather leave the current naming?

3. Splitting drawing concerns out of OnCalculate in a follow-up PR

Today OnCalculate mixes pure calculation (DataSeries writes) with drawing-side state management (ten AddText calls per bar, DrawingRectangle creation and per-bar mutation in Rectangles). The usual SDK pattern keeps OnCalculate for state writes and OnRender for read-only drawing.

Would you be open, in a future PR, to exploring whether the label management and the IB rectangle update could move to OnRender? I would rather check the direction is acceptable before investing in the refactor.

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Thanks for reviewing.