Querying a Dropdown Menu
GUI_QDMENU!(STR$, SEL%, cnt%, x%, y%, x2%, lines%)
This function queries the dropdown menu. If the user selected an entry, the entry number is stored in SEL and the function returns true, false otherwise. cnt specifies the amount of entries.
lines specifies whether the procedure should draw lines between the strings. The lowest bit decides whether there is a line between entry 1 and 2, the next one for entry 2 and 3 and so on.