[Lazarus] Simulating a DBNavigator

["Arí Ricardo Ody"]

I'm trying to simulate a DBNavigator, since the Lazarus components has certain troubles in the windows mobile devices. I'm trying to create a single database tool with my navigator and a DBGrid.
 When the “+” is clicked I insert a line in the Dataset associated and then it appears new line in the DBGrid. This was the only way I can get a new line in the DBGrid. First trouble: I must click in the new line to open it for typing.
 After type the data in the 2 new columns of the grid, I click the Post button. There is no execution errors, but the line is not included in the SQL table. May someone look the code at
http://www.4shared.com/file/CY40f7PM/myNavigator.html 
 and tell me what's wrong?
 Future problems I'd see:

    * 
 If the user alter one line of the Grid how I discover and make the update in the SQL table? In this case , does the Dataset becomes in the dsEdit mode automatically? How do I can discover, at post time, all the lines that user has altered?
    * 
    * 
 When the user clicks “Cancel” if he has clicked in the “+” button I must call the method “cancel” or “clear” of the Dataset? If the user update various lines how I ignore the alterations in these various lines?
    *
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