A DataWindow is not a grid. What it actually contains and why that makes rewrites dangerous.

A DataWindow is not a grid.

It is simultaneously:

-> A data access layer — parameterized SQL, joins across multiple tables

-> A business logic container — computed columns, validation expressions, conditional formatting

-> A rendering engine — print layouts, display formats, locale-specific output

-> A UI widget — the visual surface users interact with

All of this exists inside a single binary object in a .pbl library file.

When teams rewrite from scratch, they recover the SQL. They do not recover the computed columns or the validation expressions adjusted seventeen times over fifteen years.

This is not a documentation problem. It is a structural problem. And it is why “rebuild from scratch” is almost always the wrong answer.

What’s the most complex DataWindow you’ve ever worked with?

You can find relevant information in the specific section: https://enable-dev.com/modernization

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