[WASM] TextBox text selection behaves differently between WinUI and WASM

[darenm]

Current behavior

In the circumstance where the text content of a TextBox is longer than can be displayed in a width constrained TextBox, using the mouse to select the text causes the text content to scroll on Desktop. This does not occur as expected in WASM. This occurs with a simple TextBox and a TextBox surrounded by a ScrollViewer. We are seeing this problem in a DataGrid, but this repro is simpler.

Desktop:

Web:

Expected behavior

The WASM version behaves the same as the WinUI version.

How to reproduce it (as minimally and precisely as possible)

Here's a playground link:

http://playground.platform.uno/#5ed47dfa

Here's the repro:

UnoDatagridTextboxDragToSelect.zip

Workaround

No response

Works on UWP/WinUI

Yes

Environment

Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia

NuGet package version(s)

No response

Affected platforms

WebAssembly

IDE

Visual Studio 2022

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response

[MartinZikmund]

@darenm As @Youssef1313 investigated this, it seems that this behavior is currently not possible to influence from our side, as it is the built-in scrolling behavior of the browser. A workaround could be to keep the text entries wide enough so that the scrolling is not necessary, but apart from it seems very tricky to adjust.

[Youssef1313]

To clarify, the normal native behavior is actually that the text should scroll correctly. However, somehow this is not happening in our case. My first thought was that we are preventing the default behavior somewhere, so I went ahead and commented out all preventDefault usages in our code to see if it makes a difference, but still, we didn't get the desired native behavior.

It's likely something to fix on our side, but it's unclear to me why we are not getting the expected native behavior.

[MartinZikmund]

@darenm found the reason behind this, PR in progress

[darenm]

@MartinZikmund That's excellent news.

[darenm]

@jeromelaban can we back port this to 5.2?