bugfix(gui): Remove destroyed windows from modal stack

[tintinhamans]

A destroyed window could stay buried in the modal stack. The game could later use that dead pointer and crash.

This removes destroyed windows from the whole stack. Hidden windows keep the old behavior so they can still be shown again.

Applied to Generals and Zero Hour.

Closes #3223

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PR Summary by Qodo

Remove destroyed windows from GUI modal stacks

🐞 Bug fix 🕐 10-20 Minutes

AI Description

• Remove every modal-stack entry referencing a window when destruction begins.
• Preserve hidden-window behavior by limiting modal cleanup to destruction.
• Apply identical lifecycle handling to Generals and Zero Hour.

Diagram

graph TD
  A["Destroy window"] --> B["winDestroy"] --> C["Modal cleanup"] --> D[("Modal stack")]
  B --> E["Destroy queue"] --> F["Memory release"]

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High-Level Assessment

The dedicated destruction-only helper is the best fit: it removes buried and duplicate references immediately while preserving winUnsetModal's top-of-stack contract and hidden-window behavior. Reusing or broadening winUnsetModal would change its public semantics, while cleanup during deferred deletion would leave stale references alive longer.

Files changed (4) +44 / -10

Bug fix (4) +44 / -10

GameWindowManager.hDeclare modal-stack destruction cleanup +1/-0

Declare modal-stack destruction cleanup

• Adds the protected helper used to purge references to a window during destruction in Generals.

Generals/Code/GameEngine/Include/GameClient/GameWindowManager.h

GameWindowManager.cppPurge destroyed Generals windows from the full modal stack +21/-5

Purge destroyed Generals windows from the full modal stack

• Calls modal cleanup when destruction begins instead of only unsetting the current modal head. The pointer-to-pointer traversal removes all matching entries, including buried or duplicate references, before deferred deletion.

Generals/Code/GameEngine/Source/GameClient/GUI/GameWindowManager.cpp

GameWindowManager.hDeclare Zero Hour modal-stack destruction cleanup +1/-0

Declare Zero Hour modal-stack destruction cleanup

• Adds the protected helper used to purge references to a window during destruction in Zero Hour.

GeneralsMD/Code/GameEngine/Include/GameClient/GameWindowManager.h

GameWindowManager.cppPurge destroyed Zero Hour windows from the full modal stack +21/-5

Purge destroyed Zero Hour windows from the full modal stack

• Mirrors the Generals fix by removing every modal entry for a window as soon as destruction begins. This prevents deferred deletion from leaving dangling modal pointers.

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GameWindowManager.cpp

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Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0)

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[greptile-apps]

Greptile Summary

This PR prevents destroyed GUI windows from remaining as dangling entries in the modal stack in both Generals variants.

• Adds a helper that traverses the complete modal stack and removes every entry associated with a destroyed window.
• Invokes the cleanup when a window enters the deferred destruction path.
• Preserves the existing top-only modal behavior for hidden windows.

Confidence Score: 5/5

The PR appears safe to merge with no actionable defects identified.

The destruction path now removes all modal nodes before deferred window deletion, while every destroy-list insertion passes through that cleanup and the unlink loop safely handles buried and duplicate entries.

Important Files Changed

Filename	Overview
Generals/Code/GameEngine/Include/GameClient/GameWindowManager.h	Declares the protected modal-stack cleanup helper used by the Generals window manager.
Generals/Code/GameEngine/Source/GameClient/GUI/GameWindowManager.cpp	Moves modal cleanup to winDestroy and safely unlinks every stack node referencing the destroyed window.
GeneralsMD/Code/GameEngine/Include/GameClient/GameWindowManager.h	Declares the equivalent cleanup helper for the Zero Hour window manager.
GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GameWindowManager.cpp	Applies the same complete modal-stack cleanup to the Zero Hour destruction path.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[winDestroy called] --> B[Mark window destroyed]
    B --> C[Remove every matching modal-stack node]
    C --> D[Queue window for deferred destruction]
    D --> E[processDestroyList]
    E --> F[Send destroy notification]
    F --> G[Delete window safely]

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_{Reviews (1): Last reviewed commit: "bugfix(gui): Remove destroyed windows fr..." | Re-trigger Greptile}

[stephanmeesters]

So is the root cause that we are destroying a window that isn't on the top of the stack? Why does that happen and can it be avoided?

[stephanmeesters]

Just preference but this is maybe more readable:

void GameWindowManager::removeWindowFromModalStack( GameWindow *window )
  {
  	ModalWindow *previous = nullptr;
  	ModalWindow *modal = m_modalHead;

  	while( modal )
  	{
  		ModalWindow *next = modal->next;

  		if( modal->window == window )
  		{
  			if( previous )
  				previous->next = next;
  			else
  				m_modalHead = next;

  			deleteInstance(modal);
  		}
  		else
  		{
  			previous = modal;
  		}

  		modal = next;
  	}
  }