recreate the problem.
   1.Register a MySQL server with multiple databases.
   2. Check in the servers panel to make sure that the numeric columns
       match the original table definitions.
  3. Generate an ER model
  4. Notice that any DECIMAL columns only show length in the display
      and not the # of decimal places
   5. select a table then right click, pick preferences and notce that NONE
       of the numeric columns have lengths {including DECIMAL}.
   6. Generat a script from the ER model {all of the lengths should be fine in the script}
   7. Now, import a new ER Model into the the same model {creating a new TAB}.
   8. Switch back to the 1st TAB and all of the NUMERIC column lengths are 15 {or 15,5 for DECIMAL}.

Here is a guess. MySQL does not have SHEMA's within database BUT in a single MySQL server instance
you can address across all databases in the instance by preceding the table name with database name followed
by a period {much like using schema_name.table_name in say DB2}. So when a 2nd database was generated into the
ER model it somehow switched to something other than MySQL.

I also don't like that the ER model only show length in the display
      and not the # of decimal places for DECIMAL.

- fixed conversion

- fixed display of (precision, scale) for mysql decimal data type