Simpler workaround instead of widgetselection plugin

[f1ames]

Are you reporting a feature request or a bug?

Task

Provide detailed reproduction steps (if any)

As suggested in this comment in the bug report regarding problem with select all when non-editable element is on the beginning or end of the editable:

Styling the uneditable elements with display: inline-block or user-select: none, or adding a draggable=true attribute, makes the problem go away.

It may be worth checking if any of this solutions fits our needs and could replace widgetselection plugin (which was created as a workaround for this issue, but is more than 300 LOC so it could simplify it greatly).

I did a quick check and for simple non-editables all three seems to work:

However, when testing with image2 widgets, only display: inline-block seems to work.