Undo isn't working while you creating entity

[Integral]

Steps to reproduce:

1. Select text.
2. Assign entity.
3. Press cmd+z.
   Nothing will happend before you paste cursor.

[obuchtala]

It seems, that there is no keyboard handling on the writer level.
We should address this together with tool shortcuts.

[obuchtala]

Beyond that, it seems that the panel implementation does not use surface.transaction() or does not set before and after selection properly. Solving this would also work as a workaround, as then the selection will be updated after setting the entity.

[obuchtala]

The commit above should be fine here.
A general solution will be addressed in substance/substance#394.

[Integral]

Still here.