Cannot access table drop-down menu items

[william]

Zimbra desktop 7.3.0 beta build 13056
While composing message containing a table:
After placing cursor in an existing table and clicking on the table drop-down menu, I can select only the first menu item (Insert Table) by moving the cursor downward -- the menu disappears with any further downward movement. I can access the lower items (Table Properties, etc.) only by bypassing the first menu item and coming around to the lower ones FROM THE SIDE, from outside the menu list.