insert
Description:
Insert the child into the this at position.
If a sort function is set, the widget will actually be inserted at the calculated position and this function has the same effect of add.
If position is -1, or larger than the total number of items in the this, then the child
will be appended to the end.
Parameters:
| this |
a ListBox |
| child |
the Widget to add |
| position |
the position to insert |