VB6 ActiveX Controls: Mapping $1.5M in Custom UI Components

The average enterprise VB6 application running today isn’t just "old code"—it is a graveyard of proprietary logic buried inside custom ActiveX (OCX) controls that no longer have source code. For a Tier-1 financial institution or a global manufacturer, these controls often represent an initial investment of $1.5M or more in custom development, accumulated over decades. When these systems finally hit the wall of Windows compatibility or security compliance, the "rewrite" becomes a multi-year hostage situation.

The primary bottleneck isn't the backend SQL; it’s the UI. Specifically, activex controls mapping custom workflows require a level of forensic engineering that most modern developers simply aren't equipped to handle. You are likely staring at a grid, a chart, or a data-entry form where the business rules are inextricably linked to the visual state of a 32-bit COM component.

TL;DR: Manual modernization of VB6 ActiveX controls costs roughly $1.5M per major application and takes 18–24 months. By using Replay, enterprises can bypass the "lost source code" problem through Visual Reverse Engineering. Replay records user workflows, maps the custom ActiveX UI, and generates documented React components automatically—reducing the timeline from years to weeks and saving 70% in labor costs. Explore Replay's Visual Reverse Engineering

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The Hidden Cost of ActiveX Controls Mapping Custom Logic#

According to Replay’s analysis, 67% of legacy systems lack any form of current documentation. In the world of VB6, this is a catastrophic problem. ActiveX controls were often purchased from vendors that went bankrupt in 2008 or were built by "Star Developers" who retired a decade ago.

When you attempt activex controls mapping custom behavior manually, your team spends 40 hours per screen just trying to document "what happens when I click this." This includes:

1. •Identifying hidden state changes within the OCX.
2. •Mapping non-standard event triggers (e.g.,
   text

   BeforeUpdate
   vs
   text

   LostFocus
   ).
3. •Deciphering proprietary data-binding protocols that don't follow modern REST or GraphQL patterns.

Visual Reverse Engineering is the process of converting video recordings of legacy user interfaces into functional, documented code and design systems without needing the original source files.

Industry experts recommend that before any migration begins, an "Interface Audit" must be performed. However, doing this manually for a $1.5M UI library is a recipe for the 70% failure rate seen in enterprise rewrites.

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The $3.6 Trillion Technical Debt Crisis#

The global technical debt has ballooned to $3.6 trillion. A significant portion of this is trapped in 32-bit legacy environments that cannot be containerized or moved to the cloud. For a Senior Enterprise Architect, the goal isn't just to "make it web-based"—it's to preserve the $1.5M of functional intelligence while shedding the architectural rot.

Comparison: Manual Mapping vs. Replay Automation#

Learn more about modernizing legacy flows

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Automating ActiveX Controls Mapping Custom Workflows with Replay#

The breakthrough in activex controls mapping custom components comes from treating the UI as a visual data stream rather than a code problem. Because ActiveX controls often act as "black boxes," Replay uses its AI Automation Suite to observe the control in action.

When a user records a workflow in a legacy VB6 app, Replay captures the visual state transitions. It identifies that a specific custom OCX is acting as a "Multi-Select Data Grid with Conditional Formatting." Instead of a developer spending a week writing a specification, Replay’s Flows feature maps the architecture and its Library generates the equivalent React component.

From OCX to React: A Technical Shift#

In the old world, a custom ActiveX control might be instantiated like this in a

file:

vb
' Legacy VB6 Custom Grid Mapping
Begin MyCustomLibrary.SuperGrid ctlDataGrid 
   Height          =   4500
   Left            =   120
   TabIndex        =   4
   Top             =   1000
   Width           =   9000
   _ExtentX        =   15875
   _ExtentY        =   7938
   CustomProp      =   "DataBound-Auto"
   AllowEdit       =   -1  'True
End

The "mapping" problem is that

and are often proprietary. Replay bypasses this by observing the rendered output. It generates a modern, type-safe React component that mirrors the behavior but uses modern standards.

The Modern Equivalent (Generated by Replay)#

Here is how Replay translates that "SuperGrid" into a documented, reusable React component within your new Design System:

typescript
import React from 'react';
import { DataGrid, GridColDef } from '@mui/x-charts'; // Or your custom library

interface LegacyGridProps {
  data: any[];
  allowEdit: boolean;
  onCellChange: (params: any) => void;
}

/**
 * @component ReplayGeneratedGrid
 * @description Automatically mapped from MyCustomLibrary.SuperGrid
 * @original_location FinanceModule/InvoiceForm.frm
 */
export const ReplayGeneratedGrid: React.FC<LegacyGridProps> = ({ 
  data, 
  allowEdit, 
  onCellChange 
}) => {
  const columns: GridColDef[] = [
    { field: 'id', headerName: 'ID', width: 90 },
    { field: 'amount', headerName: 'Amount', width: 150, editable: allowEdit },
    // Replay identified these columns from visual recording
  ];

  return (
    <div style={{ height: 450, width: '100%' }}>
      <DataGrid
        rows={data}
        columns={columns}
        onCellEditCommit={onCellChange}
        disableSelectionOnClick
      />
    </div>
  );
};

By using Replay, you aren't just copying code; you are extracting the intent of the UI.

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Why 70% of Legacy Rewrites Fail#

The "Big Bang" rewrite is the most dangerous strategy in enterprise software. When dealing with activex controls mapping custom requirements, projects usually fail because:

1. •The "Shadow Logic" Trap: The UI contains validation logic (e.g., "if field A > 10, disable field B") that exists only in the OCX event handlers.
2. •Scope Creep: Without a clear inventory of components, the project expands as "hidden" screens are discovered.
3. •Loss of Domain Knowledge: The people who knew why the ActiveX control was built that way are gone.

Replay mitigates this by providing a Blueprint (Editor) that serves as the single source of truth. It allows architects to see every workflow recorded, ensuring that no custom mapping is missed.

Read about why manual rewrites are a trap

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Building a Design System from the Ashes of VB6#

One of the most valuable outputs of activex controls mapping custom processes is the creation of a unified Design System. Most VB6 apps are a hodgepodge of different OCX versions.

According to Replay’s analysis, a typical enterprise app with 200 screens uses approximately 45 unique custom controls. By mapping these visually, Replay consolidates these into a core React Component Library. This transition moves the organization from "maintenance mode" to "innovation mode."

Key Features of the Replay Platform:#

• •Library: A centralized repository of your newly mapped React components.
• •Flows: A visual map of how users navigate through the legacy system, used to plan the new architecture.
• •Blueprints: An interactive editor to refine the AI-generated code.
• •On-Premise Availability: Crucial for Financial Services and Government sectors that cannot send sensitive UI data to the cloud.

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Security and Compliance in Regulated Industries#

For sectors like Healthcare (HIPAA) or Finance (SOC2), you cannot simply outsource the activex controls mapping custom project to a low-cost manual labor shop. The risk of data exposure is too high.

Replay is built for these environments. Because the platform can be deployed on-premise, the recording and reverse engineering of the legacy UI stay within your secure perimeter. You get the speed of AI automation with the security of a local deployment.

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The Step-by-Step Guide to Mapping $1.5M in Components#

If you are tasked with this modernization, industry experts recommend this four-phase approach:

1. The Visual Audit#

Record every critical path in the legacy application using Replay. This creates the "as-is" documentation that 67% of systems lack.

2. Component Extraction#

Use Replay’s Library to identify recurring ActiveX patterns. This is where activex controls mapping custom logic becomes automated. The AI identifies that "Control_A" on Screen 1 is functionally identical to "Control_B" on Screen 50.

3. Logic Hydration#

Review the generated React components in the Blueprint editor. Add the necessary API hooks to replace the old COM data-binding.

4. Parallel Deployment#

Since Replay generates clean, documented React code, you can begin deploying the new UI piece-by-piece, or as a full SPA (Single Page Application).

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Frequently Asked Questions#

How does Replay map ActiveX controls without the source code?#

Replay uses Visual Reverse Engineering to observe the DOM (in web-based legacy) or the pixel-stream and event-hooks (in desktop-based legacy). By analyzing the visual state changes and user interactions, Replay's AI identifies the underlying logic and component structure, effectively "reconstructing" the control's intent in modern React code.

Can Replay handle highly customized 3rd-party OCX controls?#

Yes. The platform is designed specifically for activex controls mapping custom scenarios where standard documentation is missing. Whether it’s an old version of ComponentOne, Sheridan, or a completely in-house developed OCX, Replay focuses on the behavior and visual output to generate the modern equivalent.

What is the average time savings when using Replay?#

On average, Replay provides a 70% time savings compared to manual modernization. A project that would typically take 18 months of manual forensic engineering and coding can often be completed in weeks or a few months, depending on the number of unique "Flows" involved.

Is Replay SOC2 and HIPAA compliant?#

Yes. Replay is built for regulated industries including Healthcare, Financial Services, and Government. We offer On-Premise deployment options to ensure that sensitive data never leaves your controlled environment during the reverse engineering process.

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Conclusion: Stop Mapping, Start Modernizing#

The $1.5M you’ve invested in custom UI components doesn't have to be a sunk cost. By moving away from manual activex controls mapping custom efforts and embracing Visual Reverse Engineering, you can reclaim your architecture.

The era of the 24-month rewrite is over. With Replay, you can turn a legacy "black box" into a documented, modern React library in a fraction of the time.

Ready to modernize without rewriting? Book a pilot with Replay