Masafumi Hanada

This could be reproduce in [Spreadsheet demo site](https://demo.vaadin.com/spreadsheet/). When I enter some multi-byte characters in a cell, a first character is accepted as single byte character just like attached file....

The problem could be reproduce in [spreadsheet demo site](https://demo.vaadin.com/spreadsheet/) (Upload Excel files) and also local development environment. **Problem:** - cells just under frozen row are hidden by white space, though...