Help+Manual's table formatting functions are powerful but they do have some limitations. For example, you can only set a background picture for the entire table. Merging and splitting cells in a single table can also place limitations on column width adjustments.

Some of these problems can be solved by using nested tables, i.e. by inserting a second table inside the first table. Then you can apply different table properties to the second table, which can be a single cell, row or column in the "parent" table.

 

See also:

Table Properties (Reference)

How table sizing works (Reference)