Hello InJesus, you could implement an XModifyListener ( no FocusListener for cells ...). For Example:
Global oModifyListener
Global oCell
REM call this method once to set the ModifyListener.
REM to destroy the listener, call oCell.removeModifyListener( oModifyListener )
Sub SetModifyListener()
REM ( change "A1" to the cell which should trigger the callback if modified )
Dim strCellAddress : strCellAddress = "A1" REM Your Cell Address here.
oModifyListener = createUnoListener("CellModify_","com.sun.star.util.XModifyListener")
oSheet = ThisComponent.CurrentController.ActiveSheet
oCell = oSheet.getCellRangebyName( strCellAddress )
oCell.addModifyListener( oModifyListener )
End Sub
Sub CellModify_modified( oEvent )
Msgbox "Modified"
End Sub
Sub CellModify_disposing( oEvent )
Msgbox "Disposing"
End Sub