Diffentiate the following styles of combo box: a.Drop down combo box,b.Simple combo box, c.Drop down list?

And if you know know a sample program for each style

Diffentiate the following styles of combo box: a.Drop down combo box,b.Simple combo box, c.Drop down list?
A combo box is a commonly-used GUI widget. It is a combination of a drop-down list or list box and a single-line textbox, allowing the user either to type a value directly into the control or choose from the list of existing options.





A dropdown list is a user interface control GUI element similar to a list box which allows the user to choose one value from a list. When a dropdown list is inactive it displays a single value. When activated it displays (drops down) a list of values, from which the user may select one. When the user selects a new value the control reverts to its inactive state, displaying the selected value.





A dropdown list differs from a combo box in that the entry portion of a dropdown list cannot be edited. The navigation field of a web browser is an example of a combo box rather than a dropdown list.





A disadvantage of a dropdown list vs. a list box or tabs is that only one option is visible at a time and the user may not recognize the appearance of the control as containing a list of options.