>I put a combobox control in a column. I want disable interactive with the combobox (by keyboard, mouse) in normal mode. However, i want Enable input data in new records created with Append blank (grid's recordsource property = alias).
>How can i enable interactive with the combo in some rows and disable in other rows ?

Here is how to enable and disable all columns in the grid (like in the case of using an edit/save button).

thisform.grd1.setall('enabled',.F.,'column') && disable edit
thisform.grd1.setall('enabled',.T.,'column') && enable edit

To do this selectively you can do something like:
* disable edit
thisform.grd1.cl1.enabled=.F.
thisform.grd1.cl2.enabled=.F.
*enable edit
thisform.grd1.cl1.enabled=.T.
thisform.grd1.cl2.enabled=.T.