Long text are cut in the middle in page content blocks

In one project recently revealed the problem - the administrator has entered into CMS-block too long HTML. As a result, HTML was cut up to ~65000 characters, cutted up incorrectly, with a broken tag. Because of this the next time admin try to to open a CMS-block for editing - occurred js-error and the admin could not fix anything.

I propose either
1) change the field type, which stores the text of CMS-block in the database, so there may be placed a longer text (mediumtext or longtext)
or
2) make validation for add/edit CMS-block form, so that in case of field overflow, the validation error prevents incorrect data saving.