[IE9-11] Dropped content is often inserted at selection position from before DnD

[Piotrek Koszuliński]

Reproducible on ​http://tests.ckeditor.dev:1030/tests/plugins/clipboard/manual/draganddrop when dropping from outside of the editors. First DnD works, but second no - content is inserted in the wrong place (previous selection position).

[Piotrek Koszuliński]

I raised priority of this ticket because this bug is very visible in the dnd sample in SDK.

[Piotrek Koszuliński]

I pushed ​branch:t/13472. The fix is pretty simple - we stop using existing selection. Instead, we use the tricky mechanism that we created for IE8. From my tests I can see that it's much better. It does not work in some specific cases, as we know, but it does not fail when dropping from outside the editor. I'm worried only that we'll be now using it for all kinds of DnD, and the previous method worked better for internal DnD. So alternative patch may be to check data source.

[Piotrek Koszuliński]

I pushed ​branch:t/13472b with what I think is a better fix. I noticed that focus is force in the editor and this cause automatic restoring of a previous selection. The fix was to remove that line, but then it turned out that external DnD does not work on IE8. So I moved the editor.focus() call to the method that we use on IE8.