The checkbox column must not be an optional column from the "options" button in a grid.

[Pedroloma]

Describe the bug
If a grid has a check box column, this column is available in the options dialog shown from the "options" button. But the behavior must be the same as the "content-menu" column, it's meant that the check box column position must be fixed and the user cannot change it.

To Reproduce
Steps to reproduce the behavior:

1. Go to the showcase of Systelab components.
2. At the tables tab, go to the Grid section.
3. On the first grid example, click on the "Options" button.
4. The below screenshot will be shown.
5. The number of available columns is wrong, 7, actually there are 6 only columns.
6. If click on the "Remove all columns "Remove all (7)", an empty line appears at the first position on the left grid.
7. This empty line can be added at any position, but it is not shown on the right grid.
8. See error

Expected behavior
The checkbox column, if exists, must be always the first column on the grid and it must not be selectable on the options dialog.

Screenshots

When all columns are removed.