Fix: Contenteditable Elements Collapsing In LibWeb

Hey guys! Today, we're diving deep into a fascinating issue encountered in LibWeb, the heart of the Ladybird browser, specifically concerning contenteditable elements. It's a bit of a quirky bug where these elements collapse when created without initial text. Let's break it down, explore the diagnosis, and understand how this is being tackled. So buckle up, and let’s get started!

Understanding the Contenteditable Element Issue

So, the core issue revolves around contenteditable elements. When a contenteditable element is created without any text inside, it renders with zero height in Ladybird. This means it's essentially invisible, even if you've set a border or other styling. However, here’s where it gets interesting: if you create the element with text and then delete the text, it displays as expected, maintaining its height. This inconsistency is what we're aiming to resolve. To really grasp the problem, let's look at a simple HTML snippet that showcases this behavior:

<div style="border:solid 1px black;" contenteditable></div>

When you render this in Ladybird, you'll see a collapsed element. Compare that to how it looks in Chromium or Firefox, where the element maintains its height, providing a clear visual difference. This difference highlights the discrepancy we're addressing. The images included in the original issue clearly illustrate this. The Ladybird rendering shows a completely collapsed box, while the Chromium rendering displays the contenteditable div with the expected height, ready for input. This visual comparison is crucial in understanding the user experience impact of this bug. Imagine trying to type in a text box that you can't even see! That's the problem we're solving here. We're not just fixing a visual glitch; we're ensuring that users have a functional and intuitive editing experience within the Ladybird browser. This involves understanding the underlying rendering mechanisms and how they differ across browsers. By pinpointing the exact cause of this behavior in LibWeb, we can implement a targeted solution that aligns with web standards and user expectations. This meticulous approach is essential for building a robust and reliable browser. The fact that other browsers like Chromium and Firefox handle this scenario differently gives us a benchmark to aim for. We want Ladybird to not only meet but exceed these standards, providing a seamless and predictable experience for users interacting with contenteditable elements. This is a crucial step in making Ladybird a competitive and user-friendly browser.

Diving into the Diagnosis: Why is This Happening?

The diagnosis pinpoints the discrepancy to how LibWeb handles empty contenteditable elements versus elements that become empty after text deletion. The key lies in the Algorithms::delete_the_selection function. According to the specification, when text is deleted from a node, the browser should insert a <br> tag if the parent block node has no visible children and is either editable or an editing host. This <br> tag acts as a placeholder, effectively