#include <Array.au3>
#include <File.au3>
#include <GUIConstants.au3>
#include <GuiListBox.au3>
#include <ListBoxConstants.au3>

$TestGUI = GUICreate("", 343, 611, -1, -1, BitOR($GUI_SS_DEFAULT_GUI, $WS_SIZEBOX, $WS_THICKFRAME), BitOR($WS_EX_TOPMOST, $WS_EX_WINDOWEDGE))
GUISetFont(12, 400, 0, "MS Sans Serif")
GUISetBkColor(0xFFFFFF)
$SELECTOPTION = GUICtrlCreateCombo("Select Option", 8, 16, 121, 25, BitOR($CBS_DROPDOWN, $CBS_AUTOHSCROLL))
GUICtrlSetData(-1, "Option1|Option2")
GUICtrlSetFont(-1, 12, 800, 0, "MS Sans Serif")
$OPTIONLIST = GUICtrlCreateList("", 8, 64, 325, 524, BitOR($LBS_NOSEL, $WS_VSCROLL))
$FILLOPTIONDATA = GUICtrlCreateButton("Go!", 248, 32, 75, 25)
GUICtrlSetFont(-1, 12, 800, 0, "MS Sans Serif")
GUISetState(@SW_SHOW)


While 1
	$nMsg = GUIGetMsg()
	Switch $nMsg
		Case $GUI_EVENT_CLOSE
			Exit
		Case $FILLOPTIONDATA
			Select
				Case GUICtrlRead($SELECTOPTION)
					If GUICtrlRead($SELECTOPTION) = "Option1" Then
						GUICtrlSetData($OPTIONLIST, "")
						_CallOption1()
					EndIf
				Case GUICtrlRead($SELECTOPTION)
					If GUICtrlRead($SELECTOPTION) = "Option2" Then
						GUICtrlSetData($OPTIONLIST, "")
						_CallOption2()
					EndIf
			EndSelect
	EndSwitch
WEnd

Func _CallOption1()
	Local $aFileList
	_FileReadToArray("option1.txt", $aFileList)
	For $i = 1 To $aFileList[0]
		_GUICtrlListBox_AddString($OPTIONLIST, $aFileList[$i])

	Next
EndFunc   ;==>_CallOption1

Func _CallOption2()
	Local $aFileList
	_FileReadToArray("option2.txt", $aFileList)
	For $i = 1 To $aFileList[0]
		_GUICtrlListBox_AddString($OPTIONLIST, $aFileList[$i])

	Next
EndFunc   ;==>_CallOption2