Adds a dropdown list (combo box) to a custom dialog.
dlg_add_dropbox(handle, name, items) dlg_add_dropbox(handle, name, items, default_value) dlg_add_dropbox(handle, name, items, default_value, param)
hnd = dlg_new("Select Planet"); dlg_add_dropbox(hnd, "Planet", "|Mercury|Venus|Earth|Mars|Jupiter|Saturn|Uranus|Neptune", 1, "myplanet"); dlg_show(hnd); print("myplanet: ", myplanet);