[Edge] Selection made by mouse gets stuck (freezes) in some cases

[Reinmar]

First spotted in #423.

So I thought that this is a problem with CKEditor 5 itself. I also noticed some issues with selection being lost or frozen on focus/blur, but then I tested that all events are fired fine and I also noticed that the same issue is reproducible in CKEditor 4:

This means that it's not CKEditor's problem as CKEditor 4 does nothing to the selection.

CKEditor 5 sometimes fixes selections if they got fixed when passed through view->model->view pipeline but, fortunately, this doesn't seem to cause any issues. Even when I'm making selection by dragging and the engine decides that it needs to re-render the selection, it doesn't break anything.

[Reinmar]

I reported it to MS: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/11746000/, but there's a high chance that we'll have to find the trigger for this bug because it doesn't appear to be reproducible in a bare contenteditable.

[Reinmar]

It's still reproducible on http://ckeditor.com, but for some reasons I couldn't reproduce it in CKEditor 5.

However, I also noticed some issues when selection was reaching edges of inline styling and widgets. I can't reproduce them consistently, though.

[Reinmar]

Another case – #484.

Since @Mgsy confirmed that this particular case works fine in CKE4 we need to investigate how CKEditor 5 triggers it.

A couple of ideas:

• Different styling?
• Rendering after selection change which breaks selection-by-mouse-dragging. Perhaps, on Edge, when dragging from the right side of blocks, the selection is initially inserted outside of a block and our engine tries to fix that... or something :D.
• Some volatile and unrelated trigger which breaks this in Edge.

[Mgsy]

I found another issues related to selection on Edge :

1. Selection started at the marker can't be moved outside of it.

2. There's no possibility to select the marker character by character, because whole word receives selection immediately.

[Reinmar]

Isn't the latter a standard Edge's behaviour when selecting text? It often extends the selection to whole words.

[Mgsy]

Isn't the latter a standard Edge's behaviour when selecting text? It often extends the selection to whole words.

It is, but this behaviour occurs if you extend the selection to more than one word. Basically, you are able to select first word character by character.

Anyway, it's a tiny issue :)

[Mgsy]

Here is another case related to the selection on Edge.

[ma2ciek]

Some new(?) case:

1. Bold some fragment
2. Try to select text from the bold's boundary.

Result: cursor is stuck. I've checked and it works in CKE4.

[scofalik]

CKE4 or CKE5?

[ma2ciek]

It works in CKE4 and doesn't work in CKE5 beta-2 (https://ckeditor5.github.io/). I can check if it is not a regression.