[FF] Complex selection when flashes spanning across a widget

[oleq]

A followup of ckeditor/ckeditor5-engine#1431 (comment).

[Reinmar]

I checked how the selection post-fixer fixes the selection:

The fixed ranges ("before combining") are ok. The thing is, though, that they don't get combined. We select two ranges and I think that it may be breking Firefox. Those not combined ranges look reasonably, but still – Firefox starts doing weird things.

Another thing is that the whole selection is blinking. I think that we may need to stop re-rendering while it's being "done". E.g. I changed toWidget() so it stops setting cE=false. We stopped having the two-range selection problem but blinking was severe. So we'll have to fix two things here – setting a reasonable selection and avoiding blinking.

[Reinmar]

I made a quick fix which better merges ranges:

It's not valid cause it looks like this now:

		if ( combinedRanges.length > 1 ) {
			const r = new Range( combinedRanges[ 0 ].start, combinedRanges[ 1 ].end );
			combinedRanges = [ r ];
		}

But it prevented breaking the selection.

[Reinmar]

In fact... I think that we can do a quick fix here to always combine multi-range selections into a single-range selection. This only applies to Firefox and if it won't break anything in tables (which I think it won't), then we'll at least prevent breaking the selection. It will still blink, but we can handle this separately.

[jodator]

@Reinmar The proposed fix looks OK in this scenario. What about actual mutli-range selection?

I think that we cannot blindly merge mutli selection into one big selection:

1. Select some parts of text before image:
   

2. Merge combinedRanges:
   

ps.: Currently I'm debuging mergin only one of ranges and it looks like it doesn't work... only changing selection to one range looks like it "fixes" something.

[Reinmar]

I think that we cannot blindly merge mutli selection into one big selection:

We don't have to support multi-range selections. Only one browser supports them anyway. And we can make shortcuts as I don't think any user actually knows how to create such selections.

Also, we're talking about combining ranges if they were fixed. Not always.

[jodator]

Also, we're talking about combining ranges if they were fixed. Not always.

Yep only then it will happen so after testing it I'm OK with this change anyway.

I will make this change part of ckeditor/ckeditor5-engine#1450.

[Reinmar]

I extracted the "flashing" part to https://github.com/ckeditor/ckeditor5-engine/issues/1457.

The fact that Firefox was breaking the selection (you were losing the anchor) was fixed in ckeditor/ckeditor5-engine#1450 so I'm closing this ticket.