The font size on main toolbar and the pop-up toolbar is losing a cell's correct size if you force a re-populate on sheet. On either of the demo sites if you change the font size on a cell, change to a different sheet, go back to a different sheet, select the cell with the changed font. The font size displayed on both of the toolbars will go back to 11.

Reproducing Steps:

1. open demo site http://zssdemo.zkoss.org/zssdemo/
2. set font size to 18 at B1
3. select 2nd sheet
4. select back to 1st sheet
5. select B1

Expected:
Spreadsheet shows that B1's font size is 18.

Actual:
Spreadsheet shows that B1's font size is 11.