Keep inline filler also for non-collapsed selection in an active node

[f1ames]

Extracted from ckeditor/ckeditor5-engine#1355 (comment):

Perhaps it's enough to keep the current behaviour (keeping the filler as long as the selection stays in the same text node) + extending this behaviour to non empty selection + extending jumpOverInlineFiller() for these scenarios...

Inline filler is not removed from the active node (the one in which selection is) until selection is moved. It mainly prevents breaking composition. However, it is possible to extend selection during composition which causes inline filler to be removed breaking the composition sometimes.

We would like to have the same behaviour for collapsed and non-collapsed selection, so that inline filler is not removed as long as selection (or its' beginning or end) is inside active node. Also it will require adjusting jumpOverInlineFiller() for non-collapsed selection.

[f1ames]

One related issue is #4346.

[CKEditorBot]

There has been no activity on this issue for the past year. We've marked it as stale and will close it in 30 days. We understand it may be relevant, so if you're interested in the solution, leave a comment or reaction under this issue.

[CKEditorBot]

We've closed your issue due to inactivity over the last year. We understand that the issue may still be relevant. If so, feel free to open a new one (and link this issue to it).