>If you use ASSERT into a form, the ASSERT dialog is a VFP window
>and VFP start a losefocus sequence, when you push a dialog button ( ignore )
>a full reactivate sequence is fired !

Since ASSERT .F. opens a window, the behavior you see is to be expected, IMHO.

>
>Result :
>- a ASSERT command is not a hidden debug message, but it change the program state
>- all the error context is lose ( this occur with the debug windows, too )

Yes, in this case I think using DEBUGOUT would be a more appropriate choice than ASSERT.

*snipped code*

>I have seen this thousands of times, but 10' in the past a ASSERT in to grid event sent to me in crash VFP to repetition.
>Remove ASSERT and using a simple print of the trace of the application are only successful mode to correct the error.
>Result, ASSERT is little useful.

That is an entirely unfair statement and misleading for people who might be learning about this command.