Importer specification editor: issues with the options widget

[soininen]

The options widget is now a QTableWidget which supposedly lays out the options in a nice way. However, it has a few issues:

• Being a table means that the options widget breaks keyboard navigation in the specification editor. Once you tab into the table, there is no way out as Tab and Shift-Tab now navigate the table cells.
• The table cells are selectable which looks and feels weird as the background color changes.

I wonder if QGridLayout would be a better choice than cramming the options inside a table.