For interactive worksheets with scripting Action Objects may come handy. There are four types of them
Textfields work as text inputs for scripts. The script is triggered by changing text in the textfield and either pressing enter or leaving the textfield. The inserted value may be accessed using the %0 variable.
a=a+%0in script will increase number a by the entered value. Works only if a is free.
If you want the textfield to change value of a free object (or redefine dependent object), you may define that object as linked. This way you don't have to insert any script.
Buttons are meant to trigger scripts by being clicked. Although scripts can be triggered by clicking any other object (e.g. an image), using buttons for this makes your worksheet more intuitive.
Comboboxes are available only in Spreadsheet View. You may enter a list into spreadsheet cell and then turn on option Use Buttons and Checkboxes in Spreadsheet Tab of Options Dialog. The list will turn into a combobox; the selected element may be obtained using SelectedIndex Command and SelectedElement Command.